Exam 9: Testing Means: One-Sample and Two-Independent Sample T Tests

When scores are measured in a single group,the sample standard deviation is used as an estimate of the population standard deviation in the effect size formula for estimated Cohen's d.

Eta-squared is a more conservative estimate than omega-squared.

A researcher records the crying time (in minutes)of infants given oral administration of sucrose (n = 12)or tap water (n = 16)prior to a heel prick.The mean crying time in the sucrose group was 3.3±2.4 (M±SD)minutes;in the tap water group,it was 7.3±1.6 (M±SD)minutes.If the null hypothesis is that there is no difference in crying time,then what is the decision for this test?

When the proportion of variance explained by some treatment is larger than 0.25,we conclude that there is a large effect in the population.

A one-sample t test will be undefined (denominator = 0)when the same score is recorded for all participants in a study.

Effect size measures are an estimate of the size of an effect in a population.

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?

The t distribution is similar to the z distribution except

Cohen's d is a measure of proportion of variance.

When the difference between two groups is compared,the pooled standard deviation is used as an estimate for the population standard deviation in the effect size formula for estimated Cohen's d.

Normality,random sampling,and independence are all assumptions for the one-sample t test.

A researcher reports a significant effect in some population.If he computes both an eta-squared and an omega-squared effect size estimate,then which estimate will be the largest?

To compute a one-sample t test,a researcher has to know many values.Which of the following is NOT a value that the researcher must know to compute this test?

Eta-squared is computed ______ for the one-sample,and the two-independent sample t tests.

A researcher selects a sample of 32 participants who are assigned to participate in a study with one group.What are the degrees of freedom for this test?

A researcher reports that mean ratings of liking for some food are 0.8±2.4 (M±SD).If the null hypothesis was that the mean equals 0,then what is the effect size for this test using estimated Cohen's d?

A t test is associated with N degrees of freedom.

A two-independent sample t test is computed when mean differences are compared between two or more groups sampled from a population with an unknown variance.

A researcher must know the population variance in order to compute a t test.

A two-independent sample t test is used when the same participants are observed in each of two groups.