Question

Define, Describe, Identify ( give an example and an illustration if possible)

• Main effects
• Simple main effects
• Interaction (factorial)
• Post hoc test

• Test: Validity
• Test: Reliability

Answer 1

The following are concepts related to experimental designs:

In psychology, when you use the experimental method, you wish to study the effect of an Independent Variable on a Dependent Variable.

Main effect- It is the effect of one independent variable on one dependent variable (ignoring the effects of others Independent Varibles, if present). There is one main effect for every Independent Variable.

Interaction effects- If the effect of one Independent Variable on the Dependent Variable depends on another Dependent Variable.

Simple effects-  They involve breaking down of interaction effects when the researcher needs to examine a specific condition.

Example- An experiment designed to study the effects of caffeine on alertness among men and women. The main effects here would be: The impact of caffeine on alertness is men and women respectively. The interaction effect would take place say if how the caffeine influcnes alertness depends upon the gender of the person. When the researcher will conduct a study, he/she might later need to know the separate effects of caffeine on men and women. Then, simple effects will be found out by averaging the effects of gender.

Post hoc test- When you calculate ANOva between three or four groups, the results may show that there is a significant difference. However, to find out which groups differ from each other, a post hoc test is used. They analyse the effects of experiemntal data based on the probability of a Type 1 error. Some of these tests are: Bonferroni's Procedure, Rodger's method, Dunnette's correction, etc.