EXP DESIGN AO1 & AO3 Flashcards
Experimental Design
- Allocating participants to conditions
- Independent measures, repeated measures, matched pairs
Repeated measures
Each pts takes part in both conditions
Repeated measured ADVANTAGE
- Any difference between conditions likely to be due to IV not pts variables
Controls individual differences - ** (removes EV)** = compares participant’s scores from one condition with their score from condition 2 = increase internal validity
- Requires less pts
How to deal with practice and order effects
- In any repeated measures design = consider controlling P&E effects
- Can’t get rid of P&E effects = only control + reduce them
Using technique counterbalancing – specifically called ABBA
Half of pts do condition A then B
Other half do B then A
Assign pts randomly to conditions - Also, can use randomisation – presentational order of conditions is decided by use of random generators.
- Decide which half of the class gets which condition
order and effects
- Order effects can occur in a repeated measures design and refers to how the positioning of tasks influences the outcome
- e.g. practice effect or boredom effect on second task
Matched pairs
- Each person in one condition is matched with someone in the other condition on a range of important factors (dependent on study) e.g. age, gender, IQ
- control P&E effects of repeated measures + individual differences of independent measures
Matched pairs ADVANTAGE
- Controls individual differences (pts matched on key factors = controls individual differences)
- Controls P&E effects (pts do only 1 condition = no P&E effects)
Matched pairs DISADVANTAGE
- Practically difficult
- Hard to decide which factors are important (always be other potential factors that should have been matched)
How do we measure the variable we match? E.g. IQ test? - Hard to find a match – large sample size
Independent measures
- Divided randomly into 2 groups + each does a different condition of IV
Ind measures ADVANTAGE
Each pts sees only ½ of study = harder for them to work out aim of study = reduces demand characteristics
Avoids practice & order effects = pts only does 1 condition = cannot be affected by boredom/practice
Ind measures DISADVANTAGE
Each pts only provides 1 piece of data = more pts needed
Consider impact of individual differences i.e. other factors influencing IV
Randomisation
The use of chance in order to control for the effects of bias when designing materials and deciding the order of conditions
Standardisation
- All procedures are standardised in order all pts are subject to the same environments
i.e. list of exactly what will be done in the study inc standardised instructions that are read to each pt
Demand characteristics
- Features or cues in research which help participants work out what is expected of them
- participants may respond according to what they think is being investigated
=invalid results
Social desirability bias
- Pts behave to present themselves in the best light = not natural behaviour
- Researcher focuses on experimental realism = task is engaging + pts forget they are being observed = no social desirability bias