You can find out which products sell best online by comparing product sales.

Various techniques can help you understand these more complex questions.  

• Identify your questions.  What is it that you have to decide? After you place considerable time in deciding what you want to know outline your specific questions.

• Figure out who you want to ask – everyone who shops?  Only those customers who buy certain things? Only those who buy a certain dollar-value of goods? Only those who shop at certain times of day or days of week?

• How can you best ask people what you want to know?  By making them answer some questions online before they can access the rest of the Web site? By stopping them as they enter or exit the store? By getting their address and mailing them a survey? All these methods have pros and cons.

• Prizes? – Are you going to give them something for answering your questions? Samples, coupons, discounts? Do you need to offer something? It depends on how much inconvenience you are asking of them.

• Be careful of bias. If you are not asking everyone the question, make sure you have a way of picking people randomly, not just choosing people you know or are comfortable approaching.