I am a software engineer and do tend to look at things as just simple, solvable problems... Then I met my girlfriend who is completing her masters in Public Health. She has taught me of the great importance of what you mentioned (experiment design, data collection, and analysis). You can't account for all factors, but if you haven't even considered what the most important ones are, you're doing it wrong.

That being said, I hate that stories like this get more attention because everyone here is irate over how obviously wrong it is while someone's great Show HN project gets passed over.