Eds Chapter 10: The T Test For Two Independent Samples

Front 1

What is the independent-measures t test?

Back 1

A hypothesis test that uses two separate samples to evaluate the mean difference between two treatment conditions or between two different populations.

Or:

A research design that uses a separate group of participants for each treatment condition (or for each population). Also called between-subjects research design.

Front 2

In an independent-measures test, how would you view the standard error?

Back 2

A measure of how much difference is reasonable to expect between two sample means if the null hypothesis is true.

Front 3

How is the variability of different scores found?

Back 3

By adding together the variability for each of the two populations.

Front 4

What would happen if two sample sizes are different in an independent-measures test?

Back 4

The formula is biased.

Front 5

What is the defining characteristic of an independent-measures research study?

Back 5

An I.M study uses a separate group of participants to represent each of the populations or treatment conditions being compared.

Front 6

Explain what is measures by the estimated standard error in the denominator of the independent-measures t statistic?

Back 6

The estimated standard error measures how much difference is expected, on average, between a sample mean difference and the population mean difference. In a hypothesis test, mew1-mew2 is set to zero and the standard error measures how much difference is expected between the two sample means.

Front 7

What 2 factors influence the magnitude of the estimated standard error of the t statistic?

Back 7

Variability and the size of the samples.

Front 8

Although variance and sample size both influence the H test, which one has a large influence on measures of effect sizes such as Cohen's d or r^2?

Back 8

Variance

Front 9

3 assumptions underlying the independent-measures t formula

Back 9

1. Observations within each sample must be independent.

2. Two populations from which the samples are selected must be normal.

3. The two populations from which the samples are selected must have equal variance (homogeneity of variance).

Front 10

What does a relatively large value for F-max indicate?

Back 10

A large difference between two sample variances.

Front 11

Does the homogeneity of variance assumption require that two sample variances be equal?

Back 11

No. The assumption is that the two population variances are equal.