Suppose we want to find how popular a bill is in a medium-sized city of 500,000. Of course, it's not really possible to sample all of these people... it would be very expensive and time consuming.

Define a sampling method that you would use to guess the popularity of this bill. How many people would you sample this population? Would you travel door to door, or would you send out a form via mail? How would you design your sampling method, so that it is not biased?