WEEK 11 Flashcards
What is the definition of validity?
- The extent to which an effect is demonstrated in research is genuine, not produced by bogus variables and not limited to a specific context (Coolican 2019)
Internal Validity
- The extent to which an effect found in a study can be taken to be genuinely caused by manipulation of the IV
Causal Relationship: manipulation of the IV directly causes changes in the DV - To be internally valid, research needs to avoid any cofounding variables
Internal Validity E.G.
- Vincent and Lewycky’s 2009 sleep trial
-RCT
-5 week online treatment for insomnia
-118 adults
Threats to Internal Validity:
- Attrition and Mortality
-History/ politics/ natural disaster
-Sampling
-Maturation, children vs adults
-Order effects, testing and instrument issues
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Participant Expectancy
- Demand Characteristics: Research cues that help pp’s realise the study hypothesis and what is expected of them
- Hawthorne Effect: Individuals modify their behaviour in response to their awareness of being observed
- demand characteristics
- cues in the study which help pp’s work out what is expected of them
- pleasing the experimenter
-social desirability bias
-enlightenment
Observer Effect
- Researcher’s expectations for the study affect their behaviour and how pp’s respond to this
- Interactions between experimenter and pp
-Subtle differences in pp treatment
Improving validity
- Standardised procedures
- Counterbalancing: in repeated measure designs to avoid order effects
-Blinding: Eliminate possible variance due to pp and researcher expectations
Single Blinding:
- Either pp or research assistant are unaware of condition
Meda et al (2009) alcohol and driving simulator task
Double Blinding
-Both pp and research assistant unaware of condition
-Standardised for RCT trials
-Klaassen et al 2013 - caffeine and fmri scans
External Validity
- the degree to which results generalise beyond the experimental context
- the extent to which it is possible to make inferences from your sample to the larger population
WEIRD SAMPLES
- W: Western
-E: Educated
-I: Industrialised
-R: Rich
-D: Democratic
Ecological Validity
- Extent to which a research effect generalises across settings
Construct Validity:
-How should we measure psychological constructs that are abstract and not directly observable
Face Validity
- The extent to which a measure is subjectively considered to be a plausible operationalisation of the conceptual variable in question
Content Validity
- The extent to which a measure contains all the parts related to the theory of what is being measured
-Knowledge of the construct is required
Reliability
- the extent to which a measurement is reproducible or consistent over time
- reliability over time
External Reliability
Test-retest reliability
correlations of peoples scores at one time and at a later time
Inter-observer
extent to which researchers agree in their ratings
Internal Reliability
- Internal consistency of the test
-pps tend to score similarly across multiple items of a construct
Cronbach’s Alpha
- calculation of how closely related a set of items are as a group
-Easy way to compare between studies - range from 0-1, 0.7 critical value
RCT’S AND EXP VS QUASI EXP
- lab based and fully controlled
- experimental manipulation of the IV
-standardised procedures
-random allocation of pp’s to conditions - full control of IV
- random assignment into treatment and control groups
what are correlational studies
- used to determine if one factor is related to another
- non manipulated variables
questionnaires
- frequently used data collection method
- often multiple questionaire measures used within a study
-using multiple questionaires to measure similar traits
