exam 3 review

A key difference between a t statistic and a z statistic is that the standard error is _______ to compute a t statistic

Estimated

A researcher conducts a hypothesis test using a sample of n=40 from an unknown population. What is the df value for the t-statistic?

39

A researcher selects a sample of 16 women and asks them to rate how important a sense of humor is in someone they want a long -term relationship with. She records scores averaging 1.6±0.8 (M±SD) on a rating scale from -3 (not important at all) to +3 (very important). Assuming that an average score of 0 is the null hypothesis, test whether or not women find this trait important at a .05 level of significance.

Women found this trait to be important, and this result was significant, t(15) = 8.00, p< .05.

A sample of n=4 scores has SS=60 (sum of squares). What is the variance for this sample?

20

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

Cohen's d

The independent sample t-test can be only computed when:

different participants are observed one time in each group

A researcher records the number of distracters (such as noises) that preschool-aged children ignore while watching a popular Sunday morning cartoon show. Assuming that the population variance is unknown, what type of t test is appropriate for this study?

one-sample t test

Suppose a researcher observes 16 participants assigned to an experimental group (n = 16) and 16 assigned to a control group (n = 16). Scores in the experimental group were 32 ± 8 (M ± SD); scores in the control group were 32 ± 12 (M ± SD). If the null hypothesis is that the mean difference equals 0, then what is the decision for a two-independent sample t-test at a .05 level of significance?

retain the null hypothesis

The estimated standard error in the t statistic uses the ________ to estimate the ________ when the population variance is unknown.

sample variance; population variance

A professor compares final exam scores in his psychology class to final exam grades in another comparable professor's class. Assuming that the population variance of exam scores is unknown, what type of t test is appropriate for analyzing differences between these classes?

two-independent sample t test

A researcher conducts a study measuring differences in brain activity among rats placed on either a continuous or intermittent reward schedule. Assuming that the population variance in unknown, what type of t test is appropriate for this study?

two-independent sample t test

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

±2.086

Which type of error is used to compute the confidence interval for one sample selected from a population with an unknown variance?

Estimated standard error