Four Basic Canons of Science
- Determinism: Events have meaningful, systematic causes.
- Empiricism: The method of making observations. (Making observations is the best method.)
- Parsimony: If we have two competing theories, we should choose the simpler or more frugal of the two.
- Testability: You must be able to realistically test the theory (involves Validation, Falsification & Qualification).
Naturally occurring grouping variable, but analyzed like an experiment.
Independent variables vs. grouping variables
- Variable that is manipulated by experimenter
- In a Quasi-experiment, called the grouping variable (GV)
Scales of Measurement: NOIR
- Nominal: – Numbers are names only, no real order.
- – Use Frequencies and Chi-Square
- Ordinal:– rank ordered, but don’t know how far apart scores are.
- – Use nonparametric statistics
- Interval:– Tells how far apart values are, but no true 0 point. Equal interval between units.
- – Can use ANOVA
- Ratio: – like interval but with a true 0 point
- – Can use ANOVA
- Measures of Central tendency: Mean, median, mode
- Measures of Variability: Range, variance, standard deviation
- Range is the difference between the largest and smallest value
- Variance is the average squared deviation of each score from the mean
- Standard deviation is the square root of the variance.
Type I and Type II errors
Type I error: a true null hypothesis is rejected (false positive)
Type II error: Failing to regect a false null (false negative)
Factors, levels, and between/within- subjects
- Factors: # of IVs
- Levels: Treatment conditions PER IV
- Between/Within Group: Between- People are in different groups. Within- People test out all groups and compare to self.
- Statistical generalizability: Allows you to generalize to the population from which you randomly selected.
- Practical generalizability: You can generalize to similar individuals (i.e., college students)
- Situational Generalizability: Can findings from the lab be applied to real life? How is the research setting different from other settings? How were the variables (IV’s & DV’s) operationalized?
- Typically categorical
- Male, female
- 1, 2, 3, 4