Validity

Definitions

Validity:
- The extent to which an observed effect is genuine
- Does it measure what it was supposed to measured & can it be generalised beyond reseach setting ?
- (measure of accuracy - you won't get a mark for this on exam
Internal Validity:
- The ability of the study to test the hypothesis that it was designed to test
- How accuately can it test?
External Validity:
- How well the resulta of the study can be generalised outside the research setting

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Operanaliseation of Varibales
- Operationalise variable / behavioural categores to ensure the study is testing the behaviour that it was set out to test
- (not fully operationalised = low internal val.
Control of Extraneous Variables:
- Demand Characteristics:
  - Researchs want to measure REAL/NATURAL behaviour
  - If the participants change their behaviour because demand characteristics it's not natural behaviour ∴ Results not valid
- Experimenter Bias
  - If researchers are biased in the way they record behaviour - results will reflect researchers interprtation rather than natural behaviour ∴ Results not valid
- Participant Variables:
  - Participant varibale affecting results rather than variables being measured - IV not affecting DV ∴ Results not valid
Experimantal Desing ( Experiments only!)
- Independent groups desgn - Participant variables can confound results
- Repeated measures design - Order effects can confound results (although it can be reduced by counter-balancing)

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Single-Blind Technique:
- Reduces demand characteristics
- Participants don't know what group or condition they are in & ∴ cannot change their responses to suit / foil researcher
Double-Blind technique:
- Reduces demand characteristics & researcher bias
- Neither participnts nor experimenter know what each condition or group represents
Revise/Remove Questions:
- Poor face validity - questions need to be revised to relate more obviously to topic
- Low concurrent validity - reseacher should remove irrelevant questions
Improve Research Design:
- To control / overcome:
  - investigator effects,
  - demand charcteristics,
  - confounding variables,
  - social desirablility bias,
  - poorly operationalised behaviour categories

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Face Validity:
- Commonsense judgement
- Does the test seem to be assessing what it claims to be assessing?
- Where a behaviour appeares at 1st sight to represent what is being measured
Concurrent Validity:
- If test produces similar findings to another existing measure
Content Validity:
- A test has content validity is experts in that field agree that the methodology accuartely measures the desired behaviour

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Population Validity:
- Whether the findings can be applied to the target population from the limited sample of the study
Ecological Validity:
- Whether the findings can be generalised to situations outside of the research setting
Temporal Validity:
- Whether the findings can be ganeralised to other historical peroids / stay valid over time

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Population Validity:
- Uses large sample
- Using a sampling techniqque that is more likely to produce a representative sample
Ecological Validity:
- Give participants a task with high mundane realism
- If possible, conduct a field experiment / natual experiment

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