A producer of a new diet supplement pill boasts that their product helps users lose more weight than the current leading brand. The provide evidence from a double-blind placebo controlled randomized clinical trial which tested the null hypothesis H₀: µnew - µold = 0 against the alternative HA: µnew - µold 0 where µ represents the mean weight loss. Which of the following would be a Type I error?
A) Applying these results to all diet supplement pills, old and new.
B) Deciding that dieters on the new pill don't lose more weight, when in fact they do.
C) Deciding that dieters on the new pill don't lose more weight, when in fact they don't.
D) Deciding that dieters on the new pill lose more weight, when in fact they don't.
E) Deciding that dieters on the new pill lose more weight, when in fact they do.

Question

A producer of a new diet supplement pill boasts that their product helps users lose more weight than the current leading brand. The provide evidence from a double-blind placebo controlled randomized clinical trial which tested the null hypothesis H₀: µnew - µold = 0 against the alternative HA: µnew - µold > 0 where µ represents the mean weight loss. Which of the following would be a Type I error?
A) Applying these results to all diet supplement pills, old and new.
B) Deciding that dieters on the new pill don't lose more weight, when in fact they do.
C) Deciding that dieters on the new pill don't lose more weight, when in fact they don't.
D) Deciding that dieters on the new pill lose more weight, when in fact they don't.
E) Deciding that dieters on the new pill lose more weight, when in fact they do.

Quizplus · Accepted Answer

A Type I error is made when we reject the null hypothesis when it is actually true. In this scenario, rejecting the null hypothesis means deciding that the new pill is better than the old pill at helping users lose weight when in fact it is not. Therefore, option D is a Type I error.

A Producer of a New Diet Supplement Pill Boasts That