In statistics, one data collection technique is simple random sampling. This is the most simple survey done, as it is non-discriminatory towards those parties selected to participate in surveys.
There are many ways to collect data we can use direct observation, interviews, surveys, questionnaires and experiments. Direct observation and observational studies are data obtained from individuals but we do not try to influence how they answer in any form or fashion. In experiments we try to force an individual or a group to see the affects of the experiment and then make a choice. Interviews help in the area of no responsiveness to questionnaires and censuses. The quest with interviews becomes whether or not the person is telling the truth when answering the interviewer. A good interviewer will make a person feel good about giving truthful answers. Questionnaires and censuses ask individuals to answer questions, which will list certain characteristics of themselves. A survey can be put together in many forms, mostly done by using questions. Most will try to sample were there is no influence and may possibly be used as an observational study. Then there are many that are not designed to be balanced and lead to favorable responses because they are misleading. (Sullivan, 2004)