Explain the meaning of sampling survey.what are its advantages and disadvantages ?

it is a method of drawing a definite number of the individual cases or the observation from a particular universe, selecting part of a total group for investigation.the advantages of sampling surveys are; 1. very accurate 2. very reliable 3. takes less time 4. economical in nature. the disadvantage of sampling suveys are as follows; 1. problems of accuracy. 2. inadequacy of the samples. 3. chances for bias. 4. absence of informants.