A researcher examines the effectiveness of different body lotions by having 12 participants apply four different lotions to the same, unique body locations daily for two weeks.For example, lotion #1 is always applied to the right thigh, while lotion #2 is applied to the upper right arm.The participants were randomly selected at a drugstore in a busy area.What is the null hypothesis for this study?
A) Differences exist between the average effectiveness assessments of each lotion.
B) Lotions cause differences in skin quality across locations.
C) The effectiveness of the four different lotions is the same, on average.
D) The lotions are the same in terms of effectiveness.

Question

Quizplus · Accepted Answer

The null hypothesis should always state that there is no difference between groups or conditions being compared in the study. In this case, the null hypothesis should be that the effectiveness of the four different lotions is the same, on average. Option A suggests that there are differences between the lotions, which is not the null hypothesis. Option B makes a causal claim, which is not appropriate for a null hypothesis. Option D is incorrect because the researcher is specifically testing whether the lotions differ in effectiveness.

A Researcher Examines the Effectiveness of Different Body Lotions by Having