Survey is the key to accurate data collection which leads you to finding out the results and drawing conclusion(s) after proper interpretation of the data. The process of surveying is very tricky and needs extreme care. It is very important to be careful in deciding the type and number of questions and size of the sample population among which you will carry out the survey.
Sample size is very important for a survey work to accurate and meaningful. Sample size means number of units/specimen (e.g. persons/families) surveyed. If the size of the sample is very small then there are possibilities of you making wrong conclusions. For your results to be accurate, the minimum number of samples should be 100. This data should be collected using representative sampling procedure.
What is a representative sample? Say there is correlation between a particular observation and economic status of a person, then while collecting samples we should take due care that a particular number of samples is collected from each group of people having the same economic status. Similarly, if there is a correlation between age of a person and diseases, care should be taken so that samples are taken from different age groups