Experimental studies utilize blinding to prevent researchers from biasing their
ID: 3217836 • Letter: E
Question
Experimental studies utilize blinding to prevent researchers from biasing their measurements of the patients. But can they guess the treatment? In a study of a psychotherapeutic intervention, clinicians who were blinded were asked to guess what treatment their patients received. Data from that experiment are shown below. Assume that these data are indicative of the population of these treatments. Frequencies for Blinding Experiment Correct Guess Incorrect Guess a) What is the probability that a correct guess is made for a randomly chosen subject? b) If a randomly chosen subject received the placebo, what is the probability that the researcher correctly guesses the treatment?Explanation / Answer
(a) P(correct guess)=n(correct guess) / total =(30+26)/(30+26+6+11) =0.7671
(b) P(correct guess | placebo) = n(correct guess and placebo) / n(placebo) =26/(26+11) =0.7027