Flashcards in Chapter 10 Deck (10):

1

## What is a paired-samples t test and how do we use it?

###
Chapter 10 Pg. 256

> The paired-samples t test is used when we have data for all participants under two conditions a within-groups design.

> In the paired-samples t test, we calculate a difference score for every individual in the study. The statistic is calculated on those difference scores.

> We use the same six steps of hypothesis testing that we used with the z test and with the single-sample t test.

2

## What is a confidence interval, order effects and counterbalancing?

###
Chapter 10 Pg. 254

> We can calculate a confidence interval for a paired-samples t test. This provides us with an interval estimate rather than simply a point estimate. If 0 is NOT in the confidence interval, then it is NOT plausible that there is NO difference between the sample and population mean differences.

> We also can calculate an effect size (Cohen’s d ) for a paired-samples t test.

> Order effects occur when participants’ behavior is affected when a dependent variable is

presented a second time.

> Order effects can be reduced through counterbalancing, a procedure in which the different

levels of the independent variable are presented in different orders from one participant

to the next.

3

## What are the differences when comparing single sample t-tests to paired-samples t test?

###
MASTERING THE CONCEPT pg.247

10.2: The steps for the paired-samples t test are similar to those for the single-sample t test. The main difference is that for the paired-samples t test, we are comparing the sample mean difference between scores to the mean difference for the population according to the null hypothesis, rather than comparing the sample mean of individual scores to the population mean according to the null hypothesis, as we do when conducting a single-sample t test.

4

## What are the three types of t-test?

###
MASTERING THE CONCEPT Pg. 244

10.1: There are three types of t tests. We use a single-sample t test when we are comparing a sample mean to a population mean but do not know the population standard deviation. We use a paired-samples t test when we are comparing two samples and every participant is in both samples; a within-groups design. We use an independent-samples t test when we are comparing two samples and every participant is in only one sample; a between-groups design.

5

## Can a confidence interval be calculated for a paired-samples t test?

###
MASTERING THE CONCEPT Pg. 250

10.3: As we can with a z test and a single-sample t test, we can calculate a confidence interval and an effect size for a paired-samples t test.

6

## What is the confidence interval formulae for a paired-samples t-test.

###
MASTERING THE FORMULA Pg. 252

10-1: The formula for the lower bound of a confidence interval for a paired-samples t test is

Mlower = -t(sM) +Msample.

The formula for the upper bound of a confidence interval for a paired-samples t test is

Mupper = t(sM) + Msample

These are the same as for a single-sample t test, but remember that the means and standard errors are calculated from differences between pairs of scores, not individual scores.

7

## What is the Cohen's d formula for a paired-samples t-test?

###
MASTERING THE FORMULA Pg. 252

10-2: The formula for Cohen’s d for a paired-samples t statistic is:

Cohen’s d = (M – μ) / s

It is the same formula as for the single-sample t statistic, except that the mean and standard deviation are for difference scores rather than individual scores.

8

## What are order effects?

###
Chap.10, Pg. 253

■■order effects refer to how a participant’s behavior changes when the dependent variable is presented for a second time, sometimes called practice effects.

9

## What is counterbalancing?

###
Chap.10, Pg. 253

■■Counterbalancing minimizes order effects by varying the order of presentation of different levels of the independent variable from one participant to the next.

10