Statistical observation can be divided into types according to two main features: the time of registration of facts and the coverage of population units (Fig. 2.4).

Rice. 2.4. Classification of types of statistical observation

According to the time of registration of facts, statistical observation is divided into continuous (current) and discontinuous. The latter, in turn, is divided into periodic and one-time.

Current observation- this is a type of statistical observation in which systematic registration of changes in relation to the studied phenomena is carried out as they occur, for example, in traffic accidents and illegal acts. Such an observation makes it possible to study in detail the dynamics of the desired phenomenon or process.

Periodic observation- this is a type of discontinuous observation, repeated at regular intervals. To this type observation includes a population census, repeated, as a rule, every 10 years.

One-time examination is a type of discontinuous observation in which the collection of information about quantitative characteristics of the phenomenon under study is carried out directly in the process of its study. A similar re-examination may be conducted after some predetermined period of time or may not be conducted again.

According to the coverage of population units, statistical observation can be continuous and non-continuous.

Continuous observation- this is a type of statistical observation in which all units of the studied population are subjected to examination. The main prerequisite for such an observation, on which the quality of the obtained statistical information depends, is the determination of the features to be registered. The statistical practice of using continuous observation is limited due to a number of significant shortcomings of this type of study. First, there are high labor and financial resources to receive and process the entire array of information. Secondly, the relatively low timeliness of the data received, since it takes a lot of time to collect and process them. Thirdly, continuous observation, as a rule, does not provide a complete examination of all units of the population without exception. In practice, for various reasons, a greater or lesser number of units remain unobserved. The percentage of unexamined units depends on a large number of factors: the method of observation, the list of questions asked, the professionalism of the registrar, the time of year and even the hour of the day of the study. Finally, for some populations, continuous observation is not possible, for example, when the examination leads to damage or destruction of the unit under study, as in the study of quality food products or checking the service life of technical production parts. In such cases, non-continuous observation is resorted to.

Discontinuous observation- this is a type of statistical observation in which only a part of the units of the studied population is subjected to examination. The basis of such observation is the methodologically accurate choice of those units that will be subjected to the survey.

Selective observation- this is a type of non-continuous observation based on the principle of random selection of those units of the population under study that should be subjected to statistical observation. In structure sampling frame all characteristic types of units that make up the study population should be presented. Only in this case, the sample population will be able to fully convey the dependencies characteristic of the desired population, and its results will be suitable for characterizing the entire population as a whole.

A type of sampling research is momentary method, in which statistical information is collected by registering the values ​​of features from units of the sample population at some predetermined points in time. wide practical use This method was obtained in the analysis of the use of working time.

Main Array Method- this is a type of non-continuous observation, in which those units of the population that have the greatest specific gravity studied trait. Thus, the monitoring of price dynamics is carried out, as a rule, on the example of the largest cities in the country. The methodology of such a survey is based on the assumption that the exclusion of “insignificant” units from the observed set will not significantly affect the results of the study.

Monographic survey- this is a type of non-continuous observation, in which single objects of the studied population are subjected to a deep detailed examination, as a rule, representatives of characteristic or new types of social phenomena and processes. Accordingly, the purpose of a monographic survey is to characterize the already existing significant trends in the development of the phenomenon under study or to identify emerging changes. A deep study of one unit allows you to analyze both positive and negative sides its development, requiring timely elimination. The detail of the results of a monographic examination is unattainable for other types of non-continuous observation. Often, the dependencies identified in the course of such a study turned out to have eluded earlier from the field of view in the analysis of mass data. Therefore, the results of a monographic survey are indispensable for refining the program of mass surveillance.

At present, it is becoming more and more common monitoring as a special systematic observation of the state of socio-economic phenomena and processes. Of particular relevance to modern society acquires the observation of social indicators characterizing such categories as, for example, the quality of life.

All types of statistical observation achieve the greatest efficiency in mutual combination and addition. A summary classification of forms, types and methods of statistical observation is presented in Table. 2.1.

Table 2.1

Classification of forms, methods and types of statistical observation

The concept of statistical observation. Statistical observation is the initial stage of economic and statistical research. It is a scientifically organized work on the collection of massive primary data on the phenomena and processes of social life.

Requirements for statistical observation. Statistical observation must meet the following requirements: scientific or practical value, completeness of the studied facts, reliability, comparability of the studied data, scientific organization.

Organizational forms of statistical observation. There are two organizational forms: reporting and specially organized supervision.

Reporting- information about the subject of research is received in the form of mandatory reports within a certain period of time and according to approved forms.

The source of information is primary accounts in accounting and operational accounting documents.

Reporting is divided into nationwide, which is provided both to a higher organization and to the relevant bodies of state statistics, and departmental, which is provided only to higher bodies.

In addition, if reporting is provided during the year, then it is called current, according to the results of the year - annual.

Specially organized statistical observation- is the collection of information through censuses, one-time records and surveys.

Types of statistical observation. Types of observation differ in the time of data registration and in the degree of coverage of units of the study population.

According to the time of data recording, there are:

Current or Continuous observation, which is carried out systematically as the facts are accomplished. With it, a significant gap cannot be allowed between the moment of occurrence of the fact and the moment of its registration.

Discontinuous (periodic), which is repeated at regular intervals.

One-time (one-time) carried out as needed, from time to time, without observing strict periodicity, or generally carried out once.

According to the degree of coverage, there are:

solid, in which all units of the studied population are subjected to survey without exception (census, receipt of reports from enterprises).

discontinuous, in which not all units of the population are examined, but only a predetermined part of them. Non-continuous observation is divided into the following types:

Selective observation this is an observation in which the characteristics of the entire population are given according to some part of them, selected in a random order.

Main Array Method consists in the fact that that part of the units of the population is subjected to examination, in which the value of the studied trait is predominant in the entire volume.

Questionnaire survey– data collection based on the principle of voluntary completion of questionnaires by addressees. Used when not needed high accuracy information, but approximate characteristics are needed.

Monographic survey this is a detailed, in-depth study and description of individual, characteristic in some respect units of the population. (To identify shortcomings, a study of enterprises that have switched to new forms of management).

Methods of statistical observation. There are the following ways to collect data on the subject of research:

Direct this is an observation in which the registrars themselves, by measuring, weighing or counting, determine the fact to be recorded, and on this basis make entries in the observation forms.

Documentation of facts. The relevant documents serve as a source of information.

Poll- this is an observation in which the answers to the studied questions are recorded from the words of the respondent. The survey can be organized in different ways.

Expeditionary method - specially trained workers (counters) themselves establish the facts to be taken into account by direct observation on the basis of documents or interviewing relevant persons and fill out the observation form themselves.

Self-registration, i.e. the relevant documents are filled in by the interviewees themselves.

Correspondents are sent survey forms and instructions for filling them out with a request to answer the questions posed. After filling out the form of the questionnaire, the information is sent to the bodies conducting the observation.

Automated using automated statistical information system(ASIS).

Statistical observation program. When preparing for statistical observation, it is necessary to draw up an organizational plan, which includes:

Purpose of observation is the main result of the statistical study.

Object of observation- a set of units of the phenomenon under study, about which statistical data should be collected.

Unit of observation- this is the primary element of the object of statistical observation, which is the carrier of signs to be registered, and the basis of the account maintained during the survey.

Population unit- this is the primary cell from which the necessary statistical information should be obtained.

Observation Program includes a list of indicators to be studied.

Statistical forms- it's forms certain forms accounting and reporting.

Instruction includes a set of explanations and instructions on the program of statistical observation.

Errors of statistical observation. In the course of statistical observation, the following types of errors are distinguished:

registration errors arise as a result of the incorrect establishment of facts in the process of observation or their incorrect recording. They are subdivided: a) into random, which can be admitted by both respondents and registrars; b) systematic. Systematic can be: intentional (conscious) and unintentional, caused by various random reasons (carelessness, negligence, malfunction of measuring instruments);

representativeness errors, are characteristic of discontinuous observation. They arise as a result of the fact that the composition of the part of the population units selected for the survey does not fully reflect the composition of the entire population under study, although the registration of information for each unit selected for the survey was carried out accurately. They are subdivided: a) random errors of representativeness - these are deviations arising from the fact that the set of selected observation units does not fully reproduce the entire set as a whole; b) systematic errors of representativeness are deviations arising from the violation of the principles of random selection of units of the studied population. The magnitude of this error is not quantifiable.

Counting and logical control can be used to identify and eliminate errors made during registration.

Statistical observation is carried out in two forms:

By providing reports;

By conducting specially organized statistical surveys.

Statistical reporting This is the main form of statistical observation. It is a set of statistical indicators that are provided by all enterprises, organizations, institutions to state statistical bodies (and to their parent organizations) within strictly defined terms and according to strictly established forms. Statistical reporting forms are developed and approved by the National Statistical Committee.

Specially organized statistical survey, as a rule, is used for those objects that are not covered by statistical reporting. Such examinations are carried out by specialists (counters), for example, in the form of:

Census;

One-time accounting;

Thematic statistical survey.

A census is a specially organized statistical survey that characterizes a mass phenomenon or process at a certain point (period) in time. For example, a population census, a census of institutions, etc.

The census is preceded by a large preparatory work: compiling lists, breaking down administrative regions into census tracts, training personnel, etc.

One-time accounting is the study of the number and distribution of the object under study (or its parts) in a certain territory at a certain point (period) in time. For example, accounting for installed (working) equipment, accounting for the number of students by faculties.

Thematic statistical survey, as a rule, is selective in nature and solves current problems. For example, the study of family budgets.

One of the main issues of organizing statistical observation is choice of observation type. Exist classification of types of statistical observation on two main grounds:

1. In terms of completeness of coverage of population units, statistical observation may be:

solid;

Discontinuous.

continuous statistical observation has as its task the provision of a complete account of the units of the entire general population. For example, the volume of industrial production in the Republic of Belarus is obtained by accounting for manufactured products for all enterprises in the Republic of Belarus.

discontinuous statistical observation involves the registration of a part of the units of the general population and is divided into:

Monographic description;

Main array way;

Selective observation.

Monographic description(monographic observation) is used for a detailed study of single typical objects (or a small number of these objects). The main rule is the typicality of the object under study, for example:

Description of all aspects of the activities of a successful enterprise, indicating the reasons, means of success;

Description of the company's tax payments and establishing the reasons for the debt.

Main array way involves the selection of the largest units of observation, in which the main part of all the facts under study is concentrated. For example:

Only 15% of the industry's enterprises that produce 95% of the industry's products are surveyed;

5 - 6 large settlements, in which the main part of the city's market trade is concentrated.

Selective observation involves the examination of a part of the units of the general population selected in a certain order, and the obtained characteristics apply to the entire population. This is the most common type of discontinuous statistical observation, which is widely used in various fields: random inspection of product quality, random inspection of living conditions, etc.

2. According to the facts in time There are the following types of statistical observation:

current;

periodic;

One-time.

Current(or continuous) statistical observation is carried out constantly, continuously, as phenomena occur (registration of births, deaths, attendance and absenteeism, etc.).

periodic statistical observation involves the registration of the studied phenomena at certain, usually equal intervals of time (remains of raw materials in the warehouse on the 1st day of each month, students' performance at examination sessions, etc.).

lump sum statistical observation is carried out as needed, without observing strict periodicity (from time to time). For example, the census installed equipment etc.

From point of view way registration of facts are distinguished:

documentary way;

At direct observation persons conducting statistical observation receive the necessary information by personal accounting of population units directly at the survey sites: by weighing, recalculating, measuring, examining, etc. For example, a census of manufacturing equipment.

documentary way based on the use of accounting documents. It is carried out in the form of systematic entries in primary accounting documents that underlie statistical reporting (i.e., we obtain data from documents).

Poll based on the registration of answers given by the interviewees. This method of obtaining statistical information has the following varieties:

a) forwarding survey;

b) self-registration;

c) correspondent survey;

d) survey using modern computer technology(means of computer technology).

expedition survey consists in the fact that a representative of the statistical authorities travels to the place of research and conducts a survey himself and registers the answers.

Self-registration consists in the fact that a representative of the statistical authorities distributes the forms, instructs their completion and collects the completed forms (used very widely).

Correspondent poll consists in the fact that the statistical organization sends out forms and instructions for filling them out. Those who receive these forms fill them out and send them back to the address of the statistical organization. Sometimes a permanent network of correspondents is created. The sign of voluntariness is strictly observed.

In modern conditions of computerization, it is possible to receive information from correspondents via the Internet.

Statistical observation plan

Statistical observation is a complex, responsible and painstaking work. The reliability of the results of a statistical study depends on the quality of its implementation. In order to create conditions for obtaining objectively the right materials it is necessary to scientifically organize statistical observation, for which, before it is carried out, a statistical observation plan is drawn up, which consists of 2 sections:

1. Program and methodological issues of statistical observation:

1 - determination of the purpose of statistical observation;

2 - establishment of the object of observation;

3 - selection of the unit of observation;

4 - development of an observation program;

5 – choice of system of forms.

2. Organizational matters statistical observation:

1 - selection of the time of statistical observation;

2 - choice of observation site;

3 - choice of the form of observation;

4 - selection of the type of observation;

5 - choice of observation method;

6 - definition of the bodies organizing and performing the observation.

2.3.1 Program and methodological issues of the plan of statistical observation

1. Determine goal statistical observation means to give a clear formulation of the problem facing statistical research.

Establishing goals and objectives is the starting point for organizing any statistical observation. The goal should be formulated clearly, clearly, and also in detail, that is, indicating the tasks facing this statistical observation.

For example, the census.

Purpose: to determine the size and composition of the population of the Republic of Belarus and its regions and to identify patterns in their change.

2. Object of statistical observation is a set of units of the phenomenon or process under study, which is subject to statistical observation. To define an object does not mean to give a reference to the phenomenon under study. It is necessary to clearly define the composition and boundaries of the population.

For example, light industry, the clothing industry, the production of children's clothing.

When defining the object of observation, it is necessary to specify the unit of observation correctly.

3. Unit of statistical observation- this is an integral element of the studied population, which must be recorded according to certain characteristics in the process of statistical observation.

When choosing a unit of observation, it is necessary to clearly indicate which unit essential feature each unit must have in order for it to be included in the population under study (for example, in a census, citizenship).

It is necessary to distinguish between the concepts of "observation unit" and "reporting unit".

Reporting unit(accounting unit) - this is the source of information, the primary cell from which information about observation units should be received (this can be an enterprise, association, university, etc.).

4. Statistical Surveillance Program is a list of questions to be answered for each unit of observation. In other words, this is a list of signs and indicators to be registered during statistical observation.

The requirements for the questions of the observation program were formulated in the 19th century by the Belgian statistician Adolphe Quetelet:

1) the program of statistical observation should include only those questions that are necessary to solve the set goal;

2) the program should not include questions to which it is possible to receive an answer of unsatisfactory quality.

3) the program cannot include questions that can be regarded as interference in the personal questions of the respondents.

The modern theory of statistics formulates these requirements as follows:

1) the wording of questions should be clear, concise and understandable;

2) the wording of the question should be such that it can be understood by everyone in the same way, so that answers can be compared.

Let's compare two possible formulations of the question regarding the age of the respondents:

a) "age";

b) "date of birth: day ... month ... year ...".

If in the first case the question requires clarification (for example, the number of full years), then in the second - the wording of the question does not cause any variations in the answer, everyone will understand it the same and correctly.

3) for digital objects, units of measurement must be specified.

Attached to the monitoring program instruction, which explains how to understand and answer questions, gives a methodology for calculating individual indicators.

For example, return on assets can be calculated as follows:

or etc.

Similarly, the average annual value of assets can be defined in different ways: as an arithmetic average or as a chronological average.

5. Form system- these are special documents (forms, cards, etc.) in which the answers to the questions of the statistical observation program are recorded.

There are 2 form systems:

list;

Individual.

At payroll The system records the responses of several observation units in one form.

Its advantages:

It is easier to automate (transfer information to a computer);

Save paper;

Quick check of observation results.

At individual the system for each unit of observation enters its own form.

Advantage:

Can be included a large number of signs.

In the domestic government statistics most common individual system forms.

2.3.2 Organizational issues of the statistical observation plan

1. Choice time observation is the period of time to which the information received relates. For example:

a) during the census - winter 2009 - 2010;

b) profitability indicators in 2009 (in the first quarter of 2009).

Period of observation is the time during which the forms are completed: the start and end time of data collection.

critical moment(critical date) is the point in time at which the event will be recorded. For example, the 1989 census (USSR): 12 midnight from January 11 to 12 (that is, those who died after 12 midnight were also subject to the census).

2. Choice places observation has importance when studying objects moving in space (for example, the operation of transport). Then it's about setting observation point.

But often the place of observation is understood as territorial boundaries.

3. Choice forms statistical observation:

Statistical reporting;

Specially organized statistical survey (Section 2.2)

4. Choice kind statistical observation:

Solid or non-continuous;

Current, periodic or one-time (Section 2.2).

5. Choice way of conducting statistical observation:

Direct observation;

documentary way;

Interrogation method (Section 2.2).

6. Surveillance bodies:

National Statistical Committee;

Territorial statistical organizations;

Accounting and economic services of organizations, enterprises, institutions;

Specially trained people (meters), etc.

AT contemporary practice There is the following classification of the main types of statistical observation.

By coverage of population units There are two types of observation: continuous and non-continuous.

At continuous observation all units of the studied population are subjected to the survey. At the same time, due to the action of a number of factors, an insignificant percentage of the lack of coverage of the units of the studied population is possible. An example of continuous observation is the 2010 population census.

At discontinuous observation only a part of the units of the studied population is subjected to the survey. In this case, the part covered by the observation is determined in advance, i.e. a failed continuous observation cannot be regarded as a non-continuous observation. It is customary to distinguish the following types of non-continuous statistical observation: selective, monographic survey, the main array method.

Selective called an observation based on the principle of random selection of those units of the population under study that should be observed. Selective observation, with its proper organization and conduct, provides sufficiently reliable data to characterize the population under study as a whole. In many cases, it is quite possible to replace continuous accounting with them. This provides significant savings in the funds spent on the collection and processing of data.

Monographic survey is a detailed, in-depth study and description of individual units of the population, characteristic in any respect, as a rule, according to an extended program. A monographic study is carried out in order to identify existing or emerging trends in the development of the phenomenon, the availability of reserves, and to evaluate the results of economic experiments.

Main Array Method consists in the fact that the largest units are subjected to the survey, which, taken together, have a predominant share in the aggregate according to the main feature for this study. For example, in a number of sectors of the economy, large and medium-sized enterprises account for the vast majority of output, so the results of small enterprises in these sectors are practically not reflected in general statistical indicators.

According to the terms of registration, observation can be continuous (current) and discontinuous.

Continuous (current) called such observation, which is carried out constantly, and the registration of facts is carried out as they are accomplished. For example, this is how births and deaths, marriages are registered in the registry offices.

Discontinuous observation It doesn't happen all the time, it happens from time to time. In this case, discontinuous observation is of two types: periodic and one-time.

Periodic observation repeats at regular intervals. An example is the annual reporting to the state statistics authorities.

Lump is called such observation, which is carried out as needed, without observing strict periodicity, or is generally carried out once and is not repeated any more. Such an observation was the census of perennial plantations conducted in the middle of the last century.

By source of information Distinguish between direct observation, documentary observation and questioning.

direct called such an observation, in which the registrars themselves, by measuring, weighing or counting, establish the value of the attribute and, on this basis, make an entry in the observation form. In this way, for example, an inventory of fixed assets in enterprises is carried out.

Documentary observation involves recording the answers to the questions of the form on the basis of the relevant documents. An example of such observation is the collection of data on the progress of university students based on test and examination sheets, filling out statistical reporting forms based on accounting data.

Poll - this is an observation in which the answers to the questions of the form are recorded from the words of the interviewee (respondent). In this way, population censuses and public opinion polls are conducted.

The following polling methods are used in statistics:

• expeditionary;
• self-registration;
• questionnaire;
• correspondent.

Expeditionary (oral) method The survey consists in the fact that specially attracted and trained workers visit each observation unit and conduct the survey themselves and fill out the observation form. In this way, information is collected during population censuses.

With the method self-registration The forms are filled in by the respondents themselves. The duty of the employees specially involved in obtaining information is to distribute the forms to the respondents, instruct them, collect the completed forms and check the correctness of their filling.

Questionnaire method - this is the collection of statistical data using special questionnaires sent to a certain) "circle of people or published in periodicals or the Internet. As a rule, this method of obtaining information is used when conducting sociological surveys. Also, many large manufacturers household appliances, furniture and other commodities use the questionnaire method. Questionnaires are enclosed in the packaging of the goods with a request to fill out and return to the manufacturer at the specified address or are located on the website and are accompanied by an invitation to fill them out.

Essence correspondent way observation lies in the fact that the statistical authorities agree with certain persons who undertake to monitor any phenomena, processes and report the results of observations to the statistical authorities in a timely manner. In this way, the budgets of individual households are studied, the purpose of which is to obtain statistical information on the income and expenditures of the population.

Statistical observations are divided into types according to the following criteria:

by the time of data registration;

by completeness of coverage of population units;

Types of statistical observation by registration time:

Current (continuous) observation - is carried out to study current phenomena and processes. Registration of facts is carried out as they are accomplished. (registration family marriages and divorces)

Discontinuous observation - is carried out as needed, while temporary gaps in data recording are allowed:

 Periodic observation - carried out at relatively equal time intervals (population census).

 One-time observation - carried out without observing the strict frequency of its implementation.

According to the completeness of coverage of population units, the following types of statistical observation are distinguished:

Continuous observation - is the collection and receipt of information about all units of the studied population. It is characterized by high material and labor costs, insufficient information efficiency. It is used in the population census, when collecting data in the reporting form, covering large and medium-sized enterprises of various forms of ownership.

Non-continuous observation - based on the principle of random selection of units of the population under study, while in the sample population all types of units in the population must be represented. It has a number of advantages over continuous observation: reduction of time and money costs.

Non-continuous observation is divided into:

Sample observation - based on a random selection of units that are observed.

Monographic observation - consists in the examination of individual units of the population, characterized by rare qualitative properties. An example of a monographic observation: a description of the work of individual enterprises, to identify shortcomings in the work or development trends.

The method of the main array - consists in the study of the most significant, largest units of the population, which, according to the main feature, have the largest share in the population under study.

Momentary observation method - consists in conducting observations at random or constant time intervals with marks on the state of the object under study at one time or another.

Methods of statistical observation

Direct statistical observation - observation, in which the registrars themselves, by direct measurement, weighing, counting, establish the fact to be recorded.

Documentary observation - is based on the use of various kinds of accounting documents. It includes a reporting method of observation - in which enterprises submit statistical reports on their activities in a strictly mandatory manner.

Survey - is to obtain the necessary information directly from the respondent.

There are the following types of survey:

Expeditionary - registrars receive the necessary information from the interviewees and record it themselves in the forms.

Method of self-registration - the forms are filled in by the respondents themselves, the registrars only distribute the forms and explain the rules for filling them out.

Correspondent - information to the relevant authorities is reported by the staff of voluntary correspondents.

Questionnaire - the collection of information is carried out in the form of questionnaires, which are special questionnaires, it is convenient in cases where high accuracy of the results is not required.

Unsolicited - is to provide information to the relevant authorities on an unsolicited basis.

Selective observation

The concept of selective observation

Selective observation refers to a variety of discontinuous observation. It covers a selected part of the units of the general population. The purpose of selective observation is to characterize the entire population of units based on the selected part of the units. In order for the selected part to be representative (that is, to represent the entire population of units), sample observation must be specially organized. Therefore, unlike the general population, which represents the entire population of the units under study, the sample population represents that part of the units of the general population that is the object of direct observation.

For obvious reasons, the sampling method can be widely used by state statistics authorities. It allows, with significant savings in funds and costs, to obtain the necessary reliable information. The guarantee of representativeness is ensured by the use of scientifically based methods for selecting units that are to be surveyed.

It should immediately be borne in mind that when comparing indicators from the results of a sample study with characteristics for the entire general population, deviations may occur. The magnitude of these deviations is called observational error, which can be either registration error (imperfection of specifications) or representativeness error (accidental or systematic violation of the rules in the selection of units).

The following conventions are used in statistics:

N is the volume of the general population;

n is the sample size;

Average in the general population;

Average in the sample;

p is the proportion of units in the general population;

w is the proportion of units in the sample;

General dispersion;

S 2 - sample variance;

Standard deviation of a feature in the general population;

S is the standard deviation of a feature in the sample population.

Types of sampling, methods of selection and sampling errors

According to the method of selection (method of formation) of a sample of units from the general population, the following types of sample observation are common:

simple random sampling (properly random);

typical (stratified);

serial (nested);

mechanical;

combined;

stepped.

Simple random sampling (actually random) is the selection of units from the general population by random selection, but subject to the probability of choosing any unit from the general population. The selection is carried out by drawing lots or by a table of random numbers.

A typical (stratified) sample involves the division of a heterogeneous general population into typological or regionalized groups according to some significant feature, after which a random selection of units is made from each group.

For a serial (nested) sample, it is characteristic that the general population is initially divided into certain equal-sized or non-equal-sized series (the units within the series are connected according to a certain attribute), from which series are selected by random selection and then continuous observation is carried out within the selected series.

Mechanical sampling is the selection of units at regular intervals (alphabetical, temporal, spatial, etc.). During mechanical selection, the general population is divided into groups of equal size, from which one unit is then selected.

Combined sampling is based on a combination of several sampling methods.

A multi-stage sample is the formation within the general population of large groups of units at first, from which groups are formed that are smaller in size, and so on until those groups or individual units that need to be studied are selected.

Selective selection can be repeated and non-repeated. When reselecting, the probability of choosing any unit is not limited. In non-repetitive selection, the selected unit is not returned to the original population.

For the selected units, generalized indicators (average or relative) are calculated, and in the future, the results of the sample study are extended to the entire population.

The main task in sampling research is to determine sampling errors. It is customary to distinguish between mean and marginal sampling errors. For illustration, we can propose the calculation of the sampling error using the example of a simple random selection.

12 Absolute and relative values ​​in statistics. Absolute values ​​are the results of statistical observations. In statistics, unlike mathematics, all absolute values ​​have a dimension (a unit of measurement), and can also be positive and negative. Units absolute values ​​reflect the properties of units of the statistical population and can be simple, reflecting 1 property (for example, the mass of cargo is measured in tons) or complex, reflecting several interrelated properties (for example, ton-kilometer or kilowatt-hour). Units absolute values ​​can be of 3 types:

natural- are used to calculate quantities with homogeneous properties (for example, pieces, tons, meters, etc.). Their disadvantage is that they do not allow summing dissimilar quantities.

Conditionally natural- apply to absolute values ​​with homogeneous properties, but exhibiting them in different ways. For example, total weight energy carriers (wood, peat, coal, oil products, natural gas) is measured in tce - tons of reference fuel, since each of its types has a different calorific value, and 29.3 mJ / kg is taken as the standard. Similarly total school notebooks is measured in us.sh.t. - conditional school notebooks with a size of 12 sheets. Similarly, canning products are measured in a.c.b. - conditional cans with a capacity of 1/3 liter. Similarly products detergents is reduced to a conditional fat content of 40%. Cost units of measurement are expressed in rubles or in another currency, representing a measure of the value of an absolute value. They allow you to summarize even heterogeneous values, but their disadvantage is that it is necessary to take into account the inflation factor, so statistics always recalculates cost values ​​in comparable prices. Absolute values ​​can be momentary or interval. Momentary absolute values ​​show the level of the studied phenomenon or process at a certain point in time or date (for example, the amount of money in your pocket or the value of fixed assets on the first day of the month). Interval absolute values ​​are the final accumulated result for a certain period (interval) of time (for example, salary for a month, quarter or year). Interval absolute values, unlike moment ones, allow subsequent summation. The absolute statistical value is denoted X, and their total number in the statistical population is N.The number of values ​​with the same attribute value is denoted f and is called frequency (repeatability, occurrence). By themselves, absolute statistical values ​​do not give a complete picture of the phenomenon under study, since they do not show its dynamics, structure, and the relationship between parts. For these purposes, relative statistical values ​​are used. A relative statistical value is the result of the ratio of two absolute statistical values. If absolute values ​​\u200b\u200bwith the same dimension are correlated, then the resulting relative value will be dimensionless (the dimension will be reduced) and is called the coefficient.

More often instead of the name relative statistic a shorter synonym term is used - index (from lat. index- indicator, coefficient).

Depending on the types of relative absolute values ​​in the calculation of relative values, different types of indices are obtained: dynamics, plan task, plan fulfillment, structure, coordination, comparison, intensity.

13. Average values. General principles for their application The average value is a generalizing indicator that characterizes the typical level of the phenomenon. It expresses the value of the attribute, related to the unit of the population. The average always generalizes the quantitative variation of the attribute, i.e., in the average values, individual differences in the units of the population due to random circumstances are canceled out. In contrast to the average, the absolute value that characterizes the level of a feature of an individual unit of the population does not allow comparing the values ​​of the feature for units belonging to different populations. So, if you need to compare the levels of remuneration of workers at two enterprises, then you cannot compare two employees of different enterprises on this basis. The wages of the workers selected for comparison may not be typical for these enterprises. If we compare the size of wage funds at the enterprises under consideration, then the number of employees is not taken into account and, therefore, it is impossible to determine where the level of wages is higher. Ultimately, only averages can be compared, that is, how much one worker in each enterprise earns on average. Thus, there is a need to calculate the average value as a generalizing characteristic of the population. Let's dwell on some general principles the use of averages. 1. When determining the average value in each specific case, it is necessary to proceed from the qualitative content of the averaged trait, take into account the relationship of the studied traits, as well as the data available for calculation. 2. The average value must first of all be calculated on a homogeneous population. Qualitatively homogeneous aggregates allow us to obtain the grouping method, which always involves the calculation of a system of generalizing indicators. 3. General averages must be supported by group averages. For example, suppose that an analysis of the dynamics of the yield of a particular crop shows that the overall average yield in the republic is declining. However, it is known that the yield of this crop depends on soil, climatic and other conditions and is different in individual areas. 68 By grouping districts according to differences and analyzing the dynamics of group averages, it can be found that in certain groups of districts, the average yield either has not changed or is increasing, and the decrease in the overall average for the republic as a whole is due to an increase in the share of districts with lower yields in general production this agricultural crop. It is obvious that the dynamics of group averages more fully reflects the patterns of changes in yield, and the dynamics of the overall average shows only the general result. 4. A reasonable choice of the population unit for which the average is calculated is required. Let us now consider the types of averages, the features of their calculation and areas of application. Average values ​​are divided into two large classes: power averages, structural averages. Power-law averages include the most well-known and commonly used types, such as geometric mean, arithmetic mean, and mean square. The mode and median are considered as structural averages. Let us dwell on power averages. Power averages, depending on the presentation of the initial data, can be simple and weighted. A simple average is calculated from ungrouped data and has the following general form: where X, - variant (value) is averaged

18The concept and classification of time series Dynamic series is a series of numerical data placed in chronological order. They are also called dynamic series, time series. A series of dynamics characterizes the magnitude of the phenomenon under study at a particular moment or for a certain period of time. There are two main elements in each series of dynamics: 1. indicator of time t; 2. corresponding levels of development of the studied phenomenon y. As indications of time in the series of dynamics, either certain dates (moments) or separate periods (years, quarters, months, days) are used. The levels of the series of dynamics display a quantitative assessment (measure) of the development of the studied phenomenon in time. They can be expressed as absolute, relative or average values. The series of dynamics differ in the following ways: 1) In time. Depending on the nature of the phenomenon under study, the levels of the series of dynamics can refer either to certain dates (moments) in time, or to individual periods. In accordance with this, the series of dynamics are divided into moment and interval. Momentary series of dynamics reflect the state of the studied phenomena at certain dates (points) in time. An example of a moment series of dynamics is the following information on the payroll number of store employees in 2009 (Table 2): Table 2. Payroll number of store employees in 2009

A feature of the moment series of dynamics is that its levels can include the same units of the studied population. Although there are intervals in the moment series - intervals between adjacent dates in the series, the value of a particular level does not depend on the length of the period between two dates. Thus, the main part of the store's staff, making up the headcount as of 01/01/2009, continuing to work during this year, is displayed in the levels of subsequent periods. Therefore, when summing the levels of the moment series, repeated counting may occur. By means of moment series of dynamics in trade, commodity stocks, the state of personnel, the amount of equipment and other indicators that reflect the state of the studied phenomena at certain dates (points) in time are studied. Interval series of dynamics reflect the results of the development (functioning) of the studied phenomena for certain periods (intervals) of time. An example of an interval series is data on the retail turnover of a store in 2000-2004. (Table 3): Each level of the interval series is already the sum of levels for shorter periods of time. In this case, the unit of the population, which is part of one level, is not included in other levels. A feature of the interval series of dynamics is that each of its levels is made up of data for shorter intervals (sub-periods) of time. For example, summing up the turnover for the first three months of the year, you get its volume for the first quarter, and summing up the turnover for four quarters, you get its value for the year, etc. Ceteris paribus, the level of the interval series is the greater, the longer the interval, to which this level belongs. The property of summing levels for successive time intervals makes it possible to obtain series of dynamics of more enlarged periods. By means of interval series, the dynamics in trade study changes in the time of receipt and sale of goods, the amount of distribution costs and other indicators that reflect the results of the functioning of the phenomenon under study for certain periods. Statistical display of the phenomenon under study in time can be represented by series of dynamics with progressive results. Their use is due to the need to display the results of the development of the studied indicators not only for a given reporting period, but also taking into account previous periods. When compiling such series, successive summation of adjacent levels is performed. This achieves a summary generalization of the result of the development of the indicator under study from the beginning of the reporting period (year, month, quarter, etc.). d.). Dynamic series with progressive results are built when determining the total volume of retail trade turnover. So, by summarizing commodity-money reports for the last operational periods (five days, weeks, decades, etc.). 2) By the form of presentation of levels. Dynamic series can also be built, the levels of which are relative and average values. They can also be either momentary or interval. In the interval series of the dynamics of relative and average values, the direct summation of the levels in itself is meaningless, since the relative and average values ​​are derivatives and are calculated by dividing other values. 3) According to the distance between dates or time intervals, complete or incomplete series of dynamics are distinguished. Full series of dynamics take place when the dates of registration or the end of periods follow each other at equal intervals. These are equally spaced series of dynamics. Incomplete - when the principle of equal intervals is not respected. 4) According to the number of indicators, isolated and complex (multidimensional) time series can be distinguished. If one indicator is analyzed in time, we have an isolated series of dynamics. A complex series of dynamics is obtained when a system of indicators is given in chronological sequence, interconnected by the unity of a process or phenomenon.