CH.5 Research Methods in Abnormal Psychology
Science and Scientific Methods
- Science is the pursuit of systemized knowledge through observation. Scientific
observations and explanations must be testable and reliable.
Testability and Replicability
- Scientific approach requires first that propositions and ideas be stated in a clear and
- Statements, theories, and assertions must be testable. It must also be replicable and
reliable and must occur in prescribed circumstances repeatedly.
The Role of Theory
- Theory: a set of propositions meant to explain a class of phenomena.
- Hypothesis: expectations about what should occur if a theory is true.
- Theories are constructions put together by scientists. Sometimes theyre formulated by
considering previously collected data
- Operationism: each concept take as its meaning a single observable and measurable
Research Methods of Abnormal Psychology
The Case Study
- Case study: studying them one at a time and record detailed information about them.
Clinicians prepare a case study by collecting detailed historical and biographical
information on a single individual often including experiences during therapy sessions. Ex;
3 faces of eve- dissociative identity disorder
- Epidemiology: study of the frequency and distribution of a disorder in a population.
- in epidemiological research, data are gathered about the rates of a disorder and its
possible correlates in a large sample or population.
- Epidemiological research focuses on determining 3 features of a disorder: 1) Prevalence:
proportion of a population that has the disorder at a given point or period of time. 2)
Incidence: number of new cases of the disorder that occur in some period usually a year 3)
Risk factors: conditions or variables that if present increase the likelihood of developing
CDN perspectives: The Role of Abuse
- Parental mental disorder and severe abuse are the strongest risk factors
- Being raped had higher predictive value for psychosis in male participants
- Abuse is higher among first nation children
The Correlation Method - This method establishes whether there is a relationship between or among two or more
- Measuring correlation: first step is to obtain pairs of observations of the variables in
question such as height and weight for each member of a group of participants. Then the
strength of the relationship between the 2 sets of observation is calculated to determine
correlation coefficient (r).
- The stats are -1.00 to +1.00 which measures both magnitude and direction of a
relationship. An r of 0.00 indicates variables are unrelated.
- The higher the absolute value of r, the larger or stronger the relationship between the 2
- Positively related; r is positive, if X increase so does Y
- Negatively related; r is negative, if X increase and Y decreases
- Perfect relationship is when all points fall on a straight line
- Statistical significance: the likelihood that the results of an investigation are due to
chance. As the size of the correlation coefficient increases, the result is more and more
likely to be statistically significant. The greater number of observations, the smaller r
needs to be to reach statistical significance.
- Classificatory variables: naturally occurring patterns and are not manipulated by the
researcher such as age, sex, social class and body build.
- Directionality problem: it is present in many correlational research designs.
- High risk method: a research technique involving the intensive examination of people who
have a high probability of later becoming abnormal.
- Third variable problem: correlation may have been produced by a third unforeseen factor.
- It is the most powerful research technique for determining causal relationships, requiring
the manipulation of an independent variable, the measurement of a dependent variable,
and the random assignment of participants to the several different conditions being
- Basic features of experimental design: 1) Experimental hypothesis; assumption of what
will happen if a variable is manipulated. 2) Independent variable; can be manipulate, some
factor that will be under the experimenters control. 3) Random assignment; every
participant has an equal chance of being in each condition. 4) Dependent variable;
something that is expected to depend on or vary with manipulations of the independent
variable. 5) Experimental effect; when differences between groups are found to be a
function of variables in the independent variable
- The difference between group variance is the experimental effect which has been caused
by the independent variable. Individual participants within each group vary considerably
which is called within group variance. Statistical significance is tested by dividing the
between group variance by a measure of the within group variance. When the avgdifference btwn 2 groups are large relative to within group variance, the result is more
likely to be statistically significant.
- Control group: doesnt receive the experimental treatment.
- Confounds: variables such as the passage of time.
- Internal validity: when the effect can be confidently attributed to the manipulation of the
- Control groups and experimental groups are affected equally by environmental events
- The placebo effect: an improvement in a physical or psychological condition that is
attributable to a clients expectations of help rather than to any specific active ingredient
in a treatment.
- Placebo control groups: clients in such groups typically have regular contact with a
therapist and receive support and encouragement but they dont receive what is regarded
as the active ingredient in the kind of therapy under study.
- Double blind procedure: when the placebo control group design is used, clients are
randomly designed to either the treatment or the placebo group; to reduce the possibility
of bias, neither the researchers nor the clients are allowed to know to which group any
specific individual is assigned because neither the researchers nor the clients are aware of
who has been placed in the treatment and placebo control groups.
- Using a placebo control group involves several problems such as ethical issues and the
double blind placebo control group study is dif