Exam 8: Confidence Intervals, Effect Size, and Statistical Power

If a researcher runs the same study 20 times, the researcher would expect to find a mean in (or at) the _____ 95 percent of the time, with a p value of 0.05.

If an effect is significant but the effect size for the difference between the two means is small (according to Cohen's conventions), about how much overlap will there be between the two distributions?

In Cohen's d, the closer together the means of two distributions, the _____ the effect size, assuming the standard deviation is held constant.

If the population mean falls within the 95 percent confidence interval, one should fail to reject the null hypothesis.

What falls within a 90 percent confidence interval?

As N increases, the width of the confidence interval decreases.

Using a one-tailed test allows us to increase statistical power over a two-tailed test because it:

As sample size increases, the:

It is known that the population mean for the verbal section of the SAT is 500 with a standard deviation of 100.In 2006, a sample of 400 students whose family income was between $70,000 and $80,000 had an average verbal SAT score of 511.The point estimate of the mean for this group is _____ and the 95 percent confidence interval for this group is _____.

Effect size indicates the size of the difference between the sample and the null hypothesized value, unaffected by sample size.

The amount of overlap between two distributions can be decreased if their means are closer together.

Effect sizes are affected by _____ and _____.

A Cohen's d of -0.49 is what type of effect size?

When considering the results from an opinion poll, where several verbal expressions are rated for their level of annoyance, what is particularly useful about margins of error is that:

Effect size assesses the degree to which two:

Increasing sample size:

The sample mean is centered in the middle of the confidence interval.

According to a "how to stop bullying" website, 15 percent of students report experiencing bullying one to three times within the most recent month.Assume the standard deviation is 4.5 percent of students.Joseph collects data from 175 students at a medium-sized school in Iowa and finds that only 12 percent reported this rate of bullying.What is his 95 percent confidence interval?

Which of the following does NOT increase statistical power?

In Cohen's d, the farther apart the means of two distributions, the _____ the effect size, assuming the standard deviation is held constant.