Research methods in clinical psychology: An introduction for students and practitioners Chris Barker, Nancy Pistrang, and Robert Elliott

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Research methods in clinical psychologyAn
introduction for students and practitionersChris
Barker, Nancy Pistrang, and Robert Elliott

• CHAPTER 10
• The participants sampling and ethics

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Participants

• Sampling
• Ethics

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Sampling

• Who?
• who will you be studying?
• To whom can you apply the findings?
• Specifying and obtaining the sample
• quantitative and qualitative research
• Terminology
• subjects
• alternatives participants, respondents,
  co-researchers

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Sampling/ ctd.

• Universe
• Target population
• Sample
• Intended sample
• Achieved sample

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Generalising the results

• (Generalisability external validity)
• Sample population universe
• bias, plausibility
• error
• Sample size doesnt determine generalisability

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Sampling in practice

• Specify the target population
• Choose a sampling procedure
• Determine the sample size

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The target population

• Inclusion and exclusion criteria
• Homogeneous sample (narrowly defined)
• reduces extraneous variability
• Heterogeneous sample (broadly defined)
• better generalisability
• Trade-off

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Sampling procedures

• Goal an unbiased sample
• every member of target population has equal
  chance of being selected
• Convenience sampling
• bias and under-representation of certain
  populations
• Eliminating bias not always feasible
• gap between intended and achieved sample
• estimating bias

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Determining sample size

• Statistical power analysis
• depends on effect size, error rates
• Statistical power of a study likelihood of it
  detecting an effect that is actually present

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Power analysis

• Four interrelated parameters
• Sample size, N
• Alpha (p-value in statistical tests) Type I
  error rate or false positive rate. Usually plt.05.
  The chance of a finding being wrong.
• ctd./

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Power analysis/ ctd.

• Beta Type II error rate or false negative rate
  (usually .20). The chance of missing something
  that is actually there
• Statistical power 1 minus Beta
• Effect size measures the strength of the
  relationship. Depends on the statistic used.
• Cohen, J. (1992). A power primer. Psychological
  Bulletin, 112, 155-159.

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Alternative sampling approaches

• Systematic replications
• Falsificationist approach
• look for counter examples
• Popper
• Snowballing/ networking
• Purposive sampling
• Theoretical sampling
• grounded theory approach

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Ethics overview

• Central principles
• Informed consent
• Harms and benefits
• Privacy and confidentiality
• Ethics review committees
• Professional obligations

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Ethics general issues

• Ethics is a methodological issue
• Procedural decisions have ethical implications
• Ethical problems arise from viewing participants
  as objects
• Ethical considerations require methodological
  trade-offs

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Informed consent

• Full information
• Participants understanding needed
• Competence to provide consent
• Problems with deception
• Freedom of choice
• Voluntary decision (no coercion)

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Informed consent form

• Description of the study
• Explanation of its risks and benefits
• Use everyday language (no jargon)
• Offer to answer questions
• You can withdraw your consent at any time
• Researchers and participants signature

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Harms and benefits

• Minimisation of harm
• Direct harm
• emotional distress, humiliation
• Indirect harm
• withholding of benefit
• Harm to participants v. benefits to humanity

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Privacy and confidentiality

• Privacy right to not provide information to
  researcher
• Confidentiality right to withhold information
  from third parties
• Protecting confidentiality
• anonymity
• research codes
• audio/videotapes
• Limits to confidentiality

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Cost-benefit analysis

• risks versus benefits
• greater risks of new procedures
• benefits to participants versus benefits to
  others
• greater potential risks require stronger
  safeguards

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Ethics conclusions

• Ethics review committees
• Professional obligations
• to be familiar with code of conduct/ethical
  principles
• to respond to participants who need professional
  services
• Difficult choices seek advice