The disadvantage of a small sample size in psychology experiments that expect to measure a small to medium effect is that…
A) the study is underpowered, leading to an increased Type I error
B) the study is underpowered, leading to an increased Type II error.
C) the study is overpowered, leading to an increased Type I error
D) the study is overpowered, leading to an increased Type I error.

Question

The disadvantage of a small sample size in psychology experiments that expect to measure a small to medium effect is that…
A) the study is underpowered, leading to an increased Type I error 
B) the study is underpowered, leading to an increased Type II error.
C) the study is overpowered, leading to an increased Type I error 
D) the study is overpowered, leading to an increased Type I error.

Quizplus · Accepted Answer

A small sample size in psychology experiments that expect to measure small to medium effects may result in an underpowered study, leading to an increased likelihood of a Type II error, which is failing to detect a significant effect when one truly exists. A Type II error is also known as a false negative. A Type I error, on the other hand, is rejecting a null hypothesis that is actually true, also known as a false positive. Overpowering a study refers to having a sample size that is larger than necessary, which can increase the risk of a Type I error.

The Disadvantage of a Small Sample Size in Psychology Experiments