L02 Design Flashcards
Types of study methods
Experimental
Quasi-experimental
Correlational
Types of study designs
Between subject
Within subject
Matched subject
Types of variables
IV Independent variable/ DV Dependent variable
Or predictor and outcome variables
Hypothesis
Alternative/Experimental hypothesis H1
Null hypothesis H0
Experimental method
Manipulation of IV to see effects on DV
Extraneous variables can be controlled
Causality can be inferred
Criteria for causality
- Contiguity: cause (IV) precedes effect (DV)
- Correlation - must co-occur
- Absence of a tertium quid or third factor or confound that might affect results
Quasi-experimental method
There is no real manipulation of IV - cannot randomly assign participants to various conditions
More extraneous variables than experimental
Contiguity: yes
Correlational method
How variables behave naturally - no manipulation
Simultaneous measurement
No inference of causation
Extraneous variables are present
Independent variable
Variable that is manipulated by experimenter
Thought to be the cause of some effect
Exp -> one or more IV -> each 2 or more LEVELS or conditions
Dependent variable
What is measured (see levels of measurement)
Thought to be affected by changes in IV
Exp -> one or more DV
Levels of a variable
Different conditions of IV
Levels of measurement
Categorical - Nominal (includes binary variables) - Ordinal Continuous - Interval - Ratio
Nominal scale
Categories
Where numbers assigned are just labels - no meaning
eg: gender, marital status
Ordinal scale
Categories ordered according to a criterion
eg: Mineral hardness scale, position in a race
Interval scale
Continuous
Equal differences in scale represent equal differences in measure; No meaningful zero or nothing (°C)