Class #4: Variability

1. The types of studies you choose could affect:

• The way you collect data
• The statistics you use
• The conclusions you can make

2. Psychological science is about looking for and examining systemic behavioral variability. Behavior varies among individuals, changes over time and situations.

3. The Five Factor Model (OCEAN*) explains variability between people, within people and in people across time.
*OCEAN: Openness to experience, Conscientiousness, Extraversion, Agreeableness, Neuroticism

4. Some ways to check variability:

• Range: has limitations, doesn’t tell you anything about middle values
• Variance (s²): the total deviation of the scores around the mean
  • Calculate the mean
  • Subtract the mean from each score
  • Square the deviation scores
  • Add those up for the total sum of squares
  • Divide by n-1
• Standard deviation (√s²): the average deviation of the scores around the mean

5. Total Variance = Systematic Variance 🙂 + Error Variance 😦