Chapter 4: research methods
Science and abnormal behaviour:
- Nature of science:
o Way of knowing the world unlike normal everyday ways of knowing (we want facts!!)
o Science values empiricism, objectivity (it’s not a subjective thins when we say that
depression is associated with a decrease of dopamine) and replicability (we want a
bunch of different sources)
o Science demands rigorous standards of proof
o Science is a means for testing hypotheses and theoretical claims (I think autism is due
to a, b and c… I should test that!)
- Questions driving a science of psychopathology:
o What problems cause distress or impair functioning?
o Why do people behave in unusual ways? (Why somebody grabs a gun, goes to a
school and kills children?... because if we knew maybe we can prevent it!)
o How can we help people behave in more adaptive ways?
Basic components of research:
- Starts with a hypothesis or “educated guess” formulated so that they are testable.
- Research design
o A method to test hypotheses (e.g. in certain case we could use fMRI!)
o Independent variable: cause or influences behaviour, we manipulate it!!
o Dependant variable: the behaviour influenced by the independent variable, the one
we are actually measuring.
o Null hypothesis: rejected if there is a significant relationship between groups. A has
no effect on B.
Considerations in research design
- Balancing internal versus external validity:
o Internal validity: confidence that effects are due to the IV (how confident am I that
any changes in the DV is cause by the DV).
o External validity: extent to which the findings are generalizable (how confident am I
that I can take the results of my study and generalized it to the population).
- Ways to increase internal validity by minimizing confounds variable (e.g. I am testing a new
drugs. We know that some people metabolized in a better way than other, lot faster. And
maybe I have this kind of people in my group. I have to minimize this kind of confounded
o So we use control groups (they receive a placebo for example), random assignment!
o Use analogue models (for example pain)
Statistical methods and clinical meaningfulness
- Statistical methods:
o Protect against biases in evaluating data
- Statistical versus clinical significance:
o Statistical significance: the results are beyond chance
o Clinical significance: the results are clinically meaningful - Balancing statistical versus clinical significance
o Evaluate effect size
o Evaluate social validity
- Generalizability and the patient uniformity myth:
o All the patients are not the same! In the tested group, maybe someone are better
and lead the group.
Studying individual cases: case study method
- Nature of the case study:
o Extensive observation and detailed description of a client or disorder
- Limitations of the case study:
o Internal validity is typically weak
Lacks scientific rigor and suitable controls
Often entails numerous confounds
Research by correlation
- The nature of correlation:
o Statistical relation between two or more variables
o No independent variable is manipulated
o Does not imply causation
- Nature of correlation & strength of association:
o Negative (when A increases B decreases) versus positive correlation (simply means
when A increases B increases as well).
o Range from -1.0 to 0 to +1.0
- Epidemiological research: an example of correlational method
o Study incidence (number of new cases in a certain period of time), prevalence (total
number of case in a given time) and course of disorders
o Examples include AIDS, PTSD
Figure hypothetical correlations between age and sleep problems. (No correlation a bunch of dots like
a breakfast dog)
Research by experiment
- Nature of experimental research (attention it’s a research design!! Not a case study)
o Manipulation of independent variable(s)
o Observe effect on depend