1. Psychological Experimentation

2. 1. Define your population
Population = the group you are interested in.
all humans?
people with depression?
Adolescents?

3. 2. Obtain a sample to study
Sample – a subgroup of your population
In order for results to be generalizable to a population (able to infer that it is true for all members of the population), you need to obtain a representative sample.
Random sample – everyone in the population has an equal chance of being in your sample.

4. 3. Operationally define variables
Definitions should be quantifiable when possible.
Reduces subjectivity and expectancy effects.

5. 4. Manipulate the independent variable (control all other variables)
This is easier said than done.
Confounding variables – variables in a study that are not controlled for.

6. How do we control for confounding variables?
Large sample size (more likely to be representative)
Random assignment to groups (control and experimental)
Blinding
Single vs. double
Controls for
expectancy effects
Placebos or sham
treatment

7. 5. Collect and analyze data
Do basic statistics (mean, median, mode, standard deviation) to simplify data.
Compare control and experimental groups.
Run inferential statistical test (more on this later)
T test, chi squared, ANOVA