Designing Psychological Investigations

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Research Methods


  • IV varied to see the effects on the DV.
  • Lab Experiments- high on internal validity low on external validity.
  • Field Experiments- more natural enviroment but had more issues of control than a Lad study.
  • Natural Experiment- uses naturally occuring IVs but cannot conclude causality in these studies.
  • Experimental designs- Idependant designs, Matched pairs, repeated measures.

Observational Studies

  • Observing through behavioural categories.
  • Sampling methods- time and event sampling
  • Open to subjective bias- observations affected by expectations.

Correlational Analysis

  • Concerned with relationship between 2 variables.
  • Does not demonstrate causality
  • Other variables may influence any measure relationship
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Research Methods (cont)

Self-Report Methods

  • Questionnaires and interveiws
  • Structured interviews- more easily repeated.
  • Unstructured interviews- questions that evolve are dependant on answers given.
  • May involve open (respondent provides own answers) or closed (respondant chooses specific answer) questions.
  • Main problem- social desirability bias.

Case Studies

  • Detailed study of individual institution or event.
  • Generally longitudinal, following individual or group over time.
  • Allows study of complex interaction of many variables.
  • Difficult to generalise from specific cases.
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Design Issues


  • Experimental research- allows replication of study.
  • Observations- inter-observer reliability can be improved through training.
  • Self-report- internal reliability (split-half) and external reliability (test-retest)


  • Internal validity- does study test what it was intended to test?
  • External validity- can results be generalised to other situations and people?
  • Lab experiments not necessarily low in external validity.
  • If low in mundane realism, reduces generalisability of findings.
  • In observations, internal validity affected by observer bias.
  • Self-report techniques issues of face anc concurrent validity.
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Design Issues (cont)

Sampling Techniques

  • Opportunity- most easily available participants.
  • Volunteer- e.g through advert, but subject to bias.
  • Random- all members of target population must have equal chance of selection.
  • Stratified and quota- different subgroups within sample, leads to more representative sample.
  • Snowball- researcher directed to other similar potential participants
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Ethical Issues with humans

  • Informed consent and deception.
  • Harm- what constitutes too much?

Code of Conduct

  • Respect for worth and dignity of participants.
  • Right to privacy, confidentiality, informed consent and right ot withdraw.
  • Intentional deception only acceptable in some circumstances.
  • Competence- retaining high standards
  • Protection from harm and debreifing
  • Integrity- being honest and accurate in reporting.
  • Use of ethical guidlines in conjuction with ethical committees.
  • Socially sensitive research- potential social consequences for participants.
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Ethics (cont)

Ethical issues with non-humans

  • Reasons for animal use- offer opportunity for greater control and objectivity; cant use humans; physiological similarities.
  • Moral issues- sentience (experience pain and emotions)
  • Specieism- form of discrimination against non-human species.
  • Animal rights- no animal research is acceptable (Regan 1984)
  • Do animals have rights if they have no responsibilities?
  • Animal research subject to strict legislation (Animals act; BPS guidlines)
  • The 3 Rs- Reduction, Replacement, Refinement.
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