Select a representative sample: Selecting a representative sample from your sampling frame is also important for collecting valid and reliable data about the population of interest. For example, if you are sampling from a large database of customer email addresses and only wanted one response per household, you might want to cross-check each email address against mailing addresses and remove duplicates to avoid some households having a greater probability of selection. Then you would likely draw a random sample from the remaining list of email addresses.

First, thank you for providing this extensive list. I wanted to offer a quick follow up. After reading your post I decided to give Survey Junkie a try and I’ve already closed the account. Yes, I can tell it’s well organized and it is definitely a user-friendly platform. The problems I experienced were first that not one of the surveys they emailed me about were available. I did, however, complete several surveys from the site itself and I found them to be lengthy – in itself, not a problem, but 3 out of 5 told me I didn’t qualify after I’d already invested 10 – 12 minutes filling out the forms. They got more than enough information from me to be useful which is an old and highly unethical trick in market research – which happens to be my background. All in all, it was a LOT of wasted time.
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