I just seen a recent thread on this (I thought I did) and can't find anything in the search results. I was thinking of testing different markets this year with postcards. I was wondering what a suffecient number of households would be for the test. Each seperate market will be getting 3 postcards. I was thinking a total of 9 different demographics. 3 based on household income and home value and the other 6 based on age and either home value or income level. For the first 3 I would send 500+. For the other 6 it would be 275 each or I could narrow that 6 down to 4 and send it to 416. I am just wondering if 275 would be enough for an adequate test? All the postcards will be mailed out to areas I am already working in. Once the results are in, I would then next year expand to these markets, but in different areas of the city. Anybody else test different demographics like this?