I'm not catching the admission of flaw. Could you explain what I'm overlooking?
Repeat
Quote from the study,
"This study had limitations that should be considered when assessing the results. First, the sample was restricted to large apartment complexes in a single suburb in a large metropolitan area. It is unclear whether the results could be generalised to other communities. Second, the return rate of 65% was respectable, but it is low enough to raise a question about whether the sample was representative. Finally, there was no systematic method for selecting the adult in the household who would complete the survey."
Again I made a mistake I should have clicked the excerpt button so the full study isn't posted but click on the link and you will have it.
Any scientist who has any credibility will tell you a study that is based on questionaires sent through the mail is seriously flawed.