9-30.txt

Experimental Research
* Two important variables
  * IV
  * DV
Between - Subject Design
* Study design in which participants receive only one of the conditions in the experiment
* Example 1: Spaced vs Massed practice
  * We manipulate the variables
* Example 2: Introverts vs Extroverts
  * The variable is already manipulated. Introversion-Extroversion is called a subject variable.
Subject Variables
* What are the three criteria for establishing causality
  * Time precedence
  * Control for any other possibilities
  * Co-varation
* Where do subject variables fall short when it comes to establishing causality?
  * You can't control for any other possibilities
When to Use Between-Subject designs
* When participating in one condition would obviously affect performance in the other condition
* Examples:
  * Control group research
  * When deception is used
  * When the subject knows the purpose of the study
Disadvantages of using between-subjects design
* Need more subjects
* More energy, time, money
* Must attain equivalent groups
Random Assignment vs Random Selection
* Random Selection: Randomly select participants for a sample from the population
* Random Assignment: Everyone volunteering for the study has an equal chance of being place in any of the groups being formed.
Random Assignment
* Goal: To take individual difference factors that could influence the study and spread them out evenly throughout the different groups