Quiz 5

In a sample of 28 participants, a researcher estimates the 95% CI for a sample with a mean of M = 1.5 and an estimated standard error ( Sm) of 0.3. What is the confidence interval at this level of confidence?

95% CI= 0.9,2.1

The mean crying time of infants during naptime at a local preschool is 12 minutes. The school implements a new naptime routine in a sample of 25 infants and records an average crying time of 8±4.6 (M±SD) minutes. Test whether this new naptime routine reduced crying time at a .05 level of significance.

The new naptime routine significantly reduced crying time, t(24) = -4.35, p < .05.

State the critical value(s) for a t test using a two-tailed test at a .05 level of significance: t(20

±2.086

A researcher reports with 90% confidence that 31% to 37% of Americans believe in ghosts. What is the point estimate for this interval?

34%

The t distribution is similar to the z distribution except: A) it is associated with greater variability B) it is characterized by "thicker" tails compared with the z distribution C) it is associated with scores being more likely in the tails of the distribution Correct! D) all of the above

D

Two researchers (A and B) compute a one-sample t test. For both tests, the mean difference between the sample and value stated in the null hypothesis is 5, but the standard error is smaller for Researcher A. Which test is more likely to result in a decision to reject the null hypothesis?

Researcher A

Two researchers (A and B) compute a one-sample t test. For both tests, the standard error is the same, but the mean difference between the sample and value stated in the null hypothesis is smaller for Researcher A. Which test is more likely to result in a decision to reject the null hypothesis?

Researcher B

Which measure of effect size is most commonly reported with a t test?

Cohen's d