Ch. 9 Differences Among Groups

The researcher obtained a significant F from the ANOVA Omega squared was found to be .30. This is interpreted to mean that

30% of the total variance is accounted for by the treatments

Explain how the use of MANOVA helps control for experimentwise error in a study that compares three (3) treatment groups on two (2) separate measures, such as strength and endurance

A MANOVA graph can help portray the correlations between the two (2) measures and it makes it easier to see the patterns and the error rate equals the significance level

A study involves the comparison of two (2) instructional methods on achievement in math. Two classrooms are used; one method is administered in each classroom. The researcher notices that the pretest scores show differences between the two groups. The control for the influence of the pretest scores on the post-test scores, the researcher should use

ANCOVA

If the null hypothesis is false, one may assume the research hypothesis is the explanation for the results if

All other possible explanations have been controlled

A researcher sought to find out which of two (2) exercises was more effective in building endurance. One group used exercise A, and another group used exercise B. At the end of the study, the researcher should compare the two groups' scores by

An independent t test

To determine which of two (2) methods for learning a motor skill is more effective, the correct statistical analysis is

An independent t test

When the purpose of the research is to evaluate that effects of an independent variable on a dependent variable while controlling the influence of another characteristic, the best choice of a statistical analysis is

Analysis of Covariance

When the purpose of the research is to determine the effects of one independent variable (e.g., four groups) on one dependent variable (e.g., self-concept), the best choice of a statistical analysis is

Analysis of Variance

A researcher wishes to determine whether a treatment group made a significant improvement from the pretest (M=25) to the post-test (M=30). The correct statistical test to use to compare the two means is the

Dependent t test

A study that has one (1) independent variable with three (3) levels and three (3) dependent variables should be analyzed by

Discriminant analysis

For a study with two (or more) independent variables, such as type of instruction and sex, and one dependent variable, such as achievemnet, the most appropriate analysis technique is

Factorial ANOVA

A researcher wishes to compare the achievement scores of three class scheduling arrangements (schedules A, B, and C). Briefly indicate (a) what statistical technique he should use, and (b) what sequence of steps he should follow to fully analyze the data

He should use an ANOVA because there is only one dependent variable The researcher should set up a hypothesis and determine the level of significance Then choose which test statistic will be used Create a decision rule Complete the test statistic Then see your results and conclude

A researcher wishes to compare the effects of two (2) instructional methods given at two (2) age levels on achievement on a test of knowledge of rules and on a test of strategy. The appropriate statistical analysis would be

MANOVA

Three (3) levels of a treatment variable were evaluated for males and females on three (3) dependent variables. A significant F is reported for the interaction of treatment and gender on a linear composite of the three (3) dependent variables. Which statistical analysis was used?

MANOVA

Multivariate statistics have become common in many areas where differences in means are being examined. What is the difference between a multivariate and univariate statistic? Why might a researcher choose a MANOVA instead of multiple ANOVAs when analyzing data from a study?

Multivariate statistics compare more than two (2) variables Univariate statistics summarizes only one (1) variable at a time MANOVA can identify effects that are smaller than ANOVAs

Discriminant analysis differs from simple ANOVA such that discriminant analysis has

One (1) independent variable and two (2) or more dependent variables

Some studies use repeated measures to study changes within subjects. Define a repeated measure and provide an example of its use in a study

Repeated Measures is an analysis of scores for the same individuals on successive occasions, such as a series of test trails; also called split-plot ANOVA or subject x trails ANOVA Example: A study in sport psychology might investigate whether athletes' state anxiety (how nervous they feel at the time) differs before and after a game

Which one of the following statements does NOT describe an advantage of repeated measures?

Repeated measures can eliminate the influence of some unwanted variable

The t test is used to

Test whether two (2) groups differ significantly

Distinguish between what information a significant F in an ANOVA tells you and what Omega squared tells you about the ANOVA results

The F determines the ratio of explained variance to unexplained variance Each Omega squared represents the percentage of variance accounted for by that component of the ANOVA model

A two-way (factorial) ANOVA with more than one person per cell will yield F values for which of the following contrasts?

Three (3) F values, one each for rows, columns, and interaction

Use of a one-tailed vs a two-tailed test of significance of the difference between two sample means depends on

Whether the difference is expected to be in one direction only

If ANOVA has found a significant difference among four (4) treatment groups, a follow-up test such as the Scheffe is needed to determine

Which of the groups differ significantly from the others

A researcher used a t test to compare treatments and obtained a t of 3.45. One group had 48 participants and the other group had 40. The table value for significance at the .01 level was 2.64. Which of the following is the correct way to express these results?

t(86) =3.45, p < .01