5% TO 20%—THE BAD NEWS ABOUT “OBSERVATIONAL STUDIES”.

5% TO 20%—THE BAD NEWS ABOUT “OBSERVATIONAL STUDIES”. Gautam Naik had an article in the Wall Street Journal (May 3) headlined “Analytical Trend Troubles Scientists”. The troubling trend is that “observational studies often use different methodologies and arrive at different conclusions.” (“Observational studies” are one ones in which “scientists often use fast computers, statistical software and large medical data sets to analyze information previously collected by others”. I think of them as multiple regression studies.) Estimates are that there were almost 80,000 observational studies published across all scientific fields from 1990 to 2000 and over 260,000 published from 2001 to 2011. The article cites Dr. John Ioannidis as estimating that observational studies in general can be replicated only 20% of the time versus 80% of the time for controlled random trials. Another expert estimates the replication rate for observational studies at 5% to 10%.