30.11.2011 - In this booklet we present preliminary results of the Survey of unpaid work outside own household. The eldwork was carried out in the rst quarter of the year 2011 and covered a random sample of more than 13 thousand inhabitants of Poland age 15 or more. 1...

Error changing in a random manner both as to the value and as to the sign when repeatedly measuring a given quantity in unchanged conditions. The size of random error depends on the size of the sample, the variability of the observed feature and on the sampling scheme....

Sum of random error and systematic error that affect the result of a statistical survey....

Non-random sampling technique consisting in that the researcher indicates the population units that will be included in the sample, based on his knowledge of the population (eg, choosing a city to carry out primary elections, which according to the researcher's knowledge is a miniature of the...

A sequence of numbers that cannot be determined by any fixed algorithm (random numbers). Nowadays, we often identify the concept of random numbers with the concept of pseudorandom numbers....

Decomposition of time series into all possible components, i.e. trend, seasonal variations and irregular (random) variations. Two main groups of decomposition methods are distinguished: 1) mechanical methods like usual and centered moving averages; 2) analytical methods which include least squares...

Estimation of the distribution function of a random variable based on a given random sample. The value of the empirical distribution function at the point x is equal to the frequency of the event that the observations in the sample are less than the value of x....

Random number generators based on the recognition of selected experiments as random (e.g. a result of a flip of a coin or a toss of a die). The results of such experiments can be processed into the corresponding binary sequences of zeros and ones and thus random numbers with given accuracy and...

A tool for creating sequences of random numbers. Among random generators, you can distinguish physical generators (TRNG - True Random Number Generator) and program generators (PRNG - Pseudo Random Number Generator). Currently, the concept of a random number generator is often identified with a...

Generator of random numbers, which is supposed to generate random numbers using specific patterns (algorithms). Because the use of an algorithm to generate a random number that is not intended to be described by any pattern is contradictory in itself, often the numbers obtained in this way are...

Random number generator operatings on the principle of imaging the properties and physical parameters of the process, most often the electrical noise obtained in the respective electronic circuits....

Non-random sampling technique, the aim of which is to obtain a predetermined structure of the sample in terms of some characteristics. Most often, it is assumed that the structure of the sample should be consistent with the structure of the general population. It is worth mentioning that quota...

The number of statistical units included in the study set by the researcher. If the study covers the entire population of the general units, we call them a census, otherwise it is a partial examination, which in practice most often due to the costs and time of the examination takes place. In the...

Technique of sampling units to perform the assumptions of random sample selection. Since the two postulates of random selection of the sample are quite general, in particular the following techniques of sampling units can be distinguished: simple random sampling, systematic sampling, stratified...

It consists in selecting from the general population the final, individual units of the study in a direct way, where all units of sampling are simultaneously units of the study. We divide simple random sampling into simple random sampling without replacement and simple random sampling with...

Simple random sampling, in which we give each statistical unit the same probability of getting into the sample. The unit once randomly selected for the study participates in the further draw (hence the frequent name of the draw with replacement). The whole theory of classical statistical inference...

Simple random sampling, in which the result of the next draw depends on the result of the previous draw (by depleting the population by a previously drawn unit). Thus, the unit drawn for the study no longer participates in the further draw (hence the frequent name of the draw without replacement)....

A two-stage procedure, according to which the population is divided into subpopulations (subpopulations), called strata, and then from random subpopulations, randomly sampled elements are taken. In individual strata, the draw can be simple or dependent. The purpose of dividing the studied...

The sampling technique from the general population under investigation, which meets the following two conditions: 1) each unit of the population has a positive and known probability of entering the sample; 2) for each set of population units, it is possible to determine the probability that it...

The sample drawn using a simple random random sampling (with replacement)....

The technique of selecting a sample that does not meet at least one of the two conditions specified in the definition of a random sample selection. The most popular techniques of non random selection of the sample are: convenient selection, purposeful selection and quota sampling....

A random sample of sufficient size so that the distribution of statistics from the sample can be replaced with a good approximation by its limit distribution....

Sample drawn using appropriate probabilistic techniques (random sample selection)....

A random sample of too small size (number of units), so that the distribution of statistics from the sample could be replaced with a good approximation by its limit distribution....

The sample whose structure related to the examined characteristics (variables) is similar to the structure of the statistical population from which it comes. Representativeness of the sample (representative sample) can be obtained using both random (probabilistic) and non-random...

The choice of the sample is based on the rule that the statistical units get into the statistical survey randomly (not by probabilistic drawing), because they found themselves at the right time in the place where the research was carried out. This technique is widely used in surveys of consumers...

Fluctuations of a random nature, resulting from the differences between the actual and theoretical values resulting from the development of phenomena, seasonal phenomena and cyclical phenomena....

The subpopulation of the population studied is a subset of the population selected in the specified population, which is a new population (stratified random sampling). The purpose of dividing the studied population into strata, that is, stratification, is to isolate in a diverse population the...

Non-random sample selection consists in the fact that the initially selected small group of respondents is examined and each member of the group specifies (recommends) other units of the general population to be further examined. In this way the sample size starts to grow rapidly. The main...

The term 'hard coal' refers to coal of gross calorific value greater than 23 865 kJ/kg (5 700 kcal/kg) on an ashfree but moist basis and with a mean random reflectance of vitrinite of at least 0,6. Hard coal comprises together: anthracite, coking coal and other bituminous coal....