Have you ever been asked to participate in one of those “national polls” used to predict everything from presidential elections to the latest trend in fashion? No? Me either – I have never been asked to participate in a poll but somehow they sure are able to accurately predict elections, fashion trends…you name it.
How many customer surveys do I need before I can with confidence say – I know what the total population would have said given the chance to answer? Here is an interesting article and a sample-size calculator that I think goes a long way toward explaining sampling:
At this same site you will find a link to an easy to use sample-size calculator for those of us who are math challenged.