Laboratory test 1 Revision notes

• IV ~ The variable manipulated by the experimenter

• IV Levels ~ two or more condions of expereiment

• DV ~ The variable measured (subject behaviour) by the expereimenter

• Systematic EV'S ~ Confounding variable with levels varying systematically

• Random extraneous variable ~ variable randomly distributed across experiment, thus unlikely to confound.

Controlling Confounding Variables

• Random Allocation to control person variables
• Counterbalancing to control for order effects

True Experiment 

• IV fully controlled by experimenter

Quasi-experiment

• IV not fully controlled by expereimenter. No random allocation of pp's to conditions as orgnismic variables prevent this from being done

Correlation

• examines relationship between two co-variables. One variable may be considered causual hence referred to as the predictor variable, other is the predicited variable.

Independent Groups

• random allocation of pp's to seperate conditions
• Avoids order effects
• Increased effects of individual differences

Repeated Measures

• pp's perform under both conditions
• Eliminates individual differences
• Increaes order effetcs

Matched Pair's

• similar to repeated measures EXCEPT pairs equated on variables seen as relevant to behaviour examined, one member assigned to one condition, next to other, randomly
• Difficult and time consuming

Nominal

• categorical data (Chi-square)

Ordinal 

• scores are ranked. E.g. 1st,2nd,3rd in race (MW, S, W)

Interval

• equal units of intervals between scores. No absolute Zero, E.g thermometer or finishing time of racers 

Face Validity

• Does it measure what it claims to measure

Criterion related Validity

• What it measures corresponds to some independent measure of the same thing.

Predictive Validity

• Score on this predicts a score on somethig else (E.g SATS good predictive validity in predicting performance in college).

Construct Validity

• tool measures psychological concept it claims to measure