shivapps

Dear All, I am currently working with an NGO. We have a telemarketing division for propagating the cause and raising donations. We do purchase database for the calling process. The problem we face is when we get the sample before buying the database, it yields good results. But once the database is purchased, same results are not obtained. Is there a way to statistically check if the sample represents the population. I was thinking of using Hypothesis testing for the same. Since this is discrete data, again the confusion of selecting the appropriate test for the same. Require guidance or suggestions for sorting out this. Thanks, Shiva