Sampling and census, advantages and disadvantages. Population and sample. Basic notions: simple element, sampling units, sample frame, sampling errors (random, systematic).
Data collection: basic principles of making a questionnaire, unbiasedness, reliability and validity of a questionnaire. Population parameters (mean, total value, proportion, ratio).
Sampling techniques. Method description. Estimation of a population mean, total value and proportion. Confidence coefficients. Determination of sample size. Probabilistic and non probabilistic sampling.
Simple random sampling. Stratified sampling. Proportional and optimal allocation of sample in stratified sampling. Systematic sampling. Repeated systematic sampling.
Ratio estimators, regression estimators.
Cluster sampling.
Multistage sampling (two-stage and three-stage). Stratified cluster sampling. Other sampling techniques.