Ch 7

On a standard test, the population is known to have a mean of 300 and a standard deviation of 30. Those receiving an experimental treatment have a mean of 318. What is the effect size?

.60

T/F Statistical significance implies practical significance.

False

Which of the following can increase a study's statistical power? Select all that apply.

Increasing the difference between the population means, Decreasing the population standard deviation, Increasing the sample size, Using a more lenient level of significance,

A sample of people is given a weight loss pill called "Lose It." Their mean weight loss is compared to a distribution of means for weight loss of people in general. The effect size is found to be .60. What does that tell us? a)That the probability that "Lose It" had an effect on weight loss was 60% b)That the study is likely to make a Type I error. c)That the effect of "Lose It" on weight loss was too small to be detected by the statistical test. d)That taking "Lose It" lowered weight by .60 of a standard deviation.

d)That taking "Lose It" lowered weight by .60 of a standard deviation.

Dr. Sons decides to use a two-tailed test for her hypothesis, which will likely _____ her study's power. a)increase b)decrease c) not affect

decrease

Dr. Carson finds that her planned study has low power. She wants to increase it in the most straightforward way, which would be to:

increase the sample size.

According to Jacob Cohen, an effect size of .50 would be considered ______.

medium

______ refers to the probability of finding a significant result if the research hypothesis is TRUE. The _______ tells us the probability of finding a significant result if the research hypothesis is FALSE. a)Significance level; power b)Power; significance level c)Effect size; power d)Power; effect size

not a or d

You are reading about a study that found statistically significant results. You can assume the results are also practically significant if the sample size was: a)small b)large c)neither of these

small

Studies that find insignificant results are considered inconclusive. However, you may be more inclined to believe that the research hypothesis really is false IF:

the study's statistical power was high