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Research Design

In a line graph of results of a 2x2 factorial experiment, an interaction is shown by:
a) some points higher than others
b) one line higher than another
c) two lines not parallel to the x axis
d) two lines not parallel to each other

In a mixed design,
a) there is one independent variable and one dependant variable
b) one independent variable is manipulated and the other independent variable(s) is(are) not manipulated
c) At least one independent variable is tested within-subjects and the other independent variable(s) is(are) tested between-subjects.
d) the number of independent variables and dependant variables are different.

A company plans to implement a new office procedure in order to increase productivity. To find out whether the new procedure is better than the old procedure, weekly productivity over the last 6 months before the change and 6 months after the change are recorded and compared. What type of quasi-experimental design is illustrated in this example?
a) interrupted time-series
b) multiple baseline
c) cross-sequential
d) repeated treatment

Solution Preview

Please see response attached, which is also presented below. I also attached an excellent resource on factorial designs.

RESPONSE:

1. In a line graph of results of a 2x2 factorial experiment, an interaction is shown by:

a) Some points higher than others
b) One line higher than another
c) Two lines not parallel to the x-axis
d) Two lines not parallel to each other

Best answer: d) Two lines not parallel to each other

Why (d)? Often, an interaction effect when plotted results in two lines that share a point or intersect, which clearly illustrates an interaction effect, as I pointed out in my last response. However, the two lines only need NOT be parallel to demonstrate an interaction effect, they do not have to join or intersect.

As we saw in your last posting, exercise (IV) had a greater effect on weight loss (DV) when combined with dieting (IV).

More information:

Interaction effect is a research term that often confuses students, but is not that difficult if you just take it slowly and one step at a time. Let's start with a scientific definition of interaction effect; "the differing effect of one independent variable (e.g., exercise) on the dependent variable (weight loss), depending on the particular level of another independent variable (exercise and ...

Solution Summary

This solution provides the best answer for three multiple choice questions related to research design, as well as provides an explanation for the best responses and an article further discussing the factorial design.

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