1. When data is to be collected only from some members of the population, it is known as Sample Survey. When data is to be collected from each member of the population, it is known as Census Survey

19. Multistage sampling Under this method of sampling, sample is taken at several stages or levels. For example – We have to take a sample of 20 senior secondary schools of a state. At the first stage, the state may be divided into a number of districts, few districts will be selected at random. At the second stage, a district may be subdivided into number of tehsils and sample of tehsils may be taken at random. At the third stage, a number of cities and towns may be selected from each of the tehsils.

23. Purposive sampling means deliberate selection of sample units confirm to some predetermined criteria. This is also known as judgment sampling It involves selection of cases when we judge as most appropriate ones for a given study. It is based on the judgment of a researcher. It does not aim at securing a cross section of a population. The selection of samples depends upon the subjective judgment of researcher.

25. Quota Sampling Quota sampling is the frequently used method of sampling in marketing research. The basic objective of quota sampling is to control biases arising out of non-probability method by stratification and the setting of quotas for each stratum. For instance, a sample of 40 students can be selected from a group of 200 students comprising of 120 boys and 80 girls. To make the sample representative, the group of 40 should include 24 boys and 16 girls (i.e. 120: 80 = 3: 2). Quota sampling offer benefits of speed, economy and simplicity. It is widely used in market surveys and public opinion polls. DR G K KALKOTI25