What is validity?
How accurate the results of an experiment are
(does it measure what it’s meant to)
What is reliability?
the consistency/agreement of the measuring device
(Res needs to be repeatable and achieve same results on another occasion)
How do psychologists improve reliability?
(4)
standardise instructions (ppt receive exactly same instruction)
carefully controlled prodcedures (make sure carry out experiment in exactly same way each time)
reducing confounding/extraneous variables
Use non biased sample
What 2 ways can you assess reliability?
-Test-retest
-Interobserver reliability
What’s test retest
Test taken on 2 occasions and results correlated)- correlation of 0.8 or above indicate high reliability
What is inter-observer reliability?
Observers independently rate observation. Correlation of 0.8 or above indicate high reliability
What is test-retest reliability?
To take the test twice and see if the results correlate
What is internal validity?
Are the results of an experiment really due to IV affecting DV
What is external validity?
Can generalize the results to real life situations
Give the 3 types of external validity
Ecological
Temporal
Population
What is ecological validity?
Can the results be generalized to other situations/places
What is temporal validity?
Can the results be generalized to other times in history
What is population validity?
Can the results be generalized to other people
What are the 2 ways of assessing validity
Face validity
Concurrent validity
Define face validity
does test look like it’s measuring what it’s meant to measure
Define concurrent validity
does the test give a similar result to an existing similar test
How can we improve validity in experiments
standardise procedures
Use control group
Reduce demand characteristics
How can we improve validity in questionnaires
reduce social desirability bias
Anonymity
Check questions relate to whats been measured
How can we improve validity in observations?
use covert observations
Use clear behavioural categories
Do pilot study
Train observers