Chapter 10- T test for related samples

An advantage of the related-samples design is_____.

that it reduces standard error

Related or dependent sample

Participants in each group or sample are related

Between-Subjects Design

A research design in which different participants (2) are observed at each level of the IV condition or sample group.

Repeated measures design

A research design in which the same participants are observed in each sample. This is the most common related samples design.

____ is used to measure the proportion of variance accounted for by the treatment.

Eta squared

Omega squared is a more biased measure of effect of effect size to eta squared

False

APA results

Must include the IV conditions, the DV, df, obtained test statistic, sample means, p value relative to alpha, whether one or two tailed an effect size, and confidence interval.

Compared to an independent sample study, a related samples study tends to have a greater likelihood of detecting a treatment effect

True

The t statistic for related-samples design is structurally similar to the one sample t statistic, except it is based on the difference scores.

True

There are two assumptions you make to compute the related samples t test

1. Normality- we assume data in the population of differences scores are normally distributed 2. Independence within groups- we assume that difference scores were obtained from different individuals within

The related-samples design is also known as a ______.

within subjects design

There are four assumptions for the independent t Test that need to be met to assure results are valid

1. Normality: There are two ways to assure normality- increase sample size n is greater than 30 and a sample from a normal population distribution. 2. Independence: The probability outcomes for participants in the sample are independent of the probability outcomes of the participants in other samples. 3. Random Sampling: The probability of being selected in the sample conditions of the IV need to remain equal for all participants. 4. Homogeneity of Variance: The variances between the sample conditions should remain similar and not be statistically different.

Advantages for selecting related samples

1. Selecting related samples can be more practical (May provide a better way to test your hypotheses) 2. Selecting related samples minimizes standard error (Computing difference scores prior to computing the test statistic eliminates the between-persons source of error, which reduces the estimate of standard error) 3. Selecting related samples increases power (Reducing the estimate for standard error will increase the value of the test statistic)

Matched pairs design

A research design in which participants are selected and then matched experimentally or naturally, based on the common characteristics or traits they share Matching through experimental manipulation is typical for experiments in which the researcher manipulates the traits or characteristics used to match the participants Matching through natural occurrence is typical for quasi-experiments in which participants are matched based on their preexisting traits or characteristics

Independent Measure or Independent Samples

A research design that involves 2 or more sample conditions with different participants in each sample.

Two types of repeated measures designs

1. Pre-post design - type of repeated measures design in which researchers measure a dependent variable for participants before (pre) and following (post) some treatment. 2. Within-subjects design - type of repeated measures design where researchers observe the same participants across many treatments but not necessarily before and after a treatment

Participants can be related in two ways:

1. They are observed in more than one group (repeated measures design) 2. They are matched, experimentally or naturally, based on the common characteristics or traits that they share (matched-pairs design).

Independent-samples t Test or Two independent-samples t Test

A statistical procedure used to test hypotheses about the difference between two population means using a between subjects design.

A research design that uses one group of participants to study at two different occasions is called ______.

related sample t test