Convenience Sampling - A convenience sample is a group of individuals who are readily available to participate in a study. That is, the choice of the sample is left completely to the convenience of the investigator. The cost involve in picking up the sample is minimum and the cost of data collection is also generally low. For example, the investigator wants to study the demand for the types of soft drinks. The interviewer can go to some soft drinks shop and can interview shopkeepers who happens to come to that particular shop and ask them questions regarding their choice for soft drinks. Convenience sample suffers from excessive bias from known and unknown source and also there is no way that the possible errors can be quantified. It is good for taking a quick opinion poll developing tools such as questionnaire or interview schedule and for preliminary study before developing an elaborate research proposal.