RESEARCH METHOD COHEN ok

266 EX POST FACTO RESEARCH
X
O
A study by Borkowsky (l970) was based upon
this kind of design. He attempted to show a
relationship between the quality of a music
teacher’s undergraduate training (X) and his
subsequent effectiveness as a teacher of his subject
(O). Measures of the quality of a music teacher’s
college training can include grades in specific
courses, overall grade average and self-ratings,
etc. Teacher effectiveness can be assessed by
indices of pupil performance, pupil knowledge,
pupil attitudes and judgement of experts, etc.
Correlations between all measures were obtained
to determine the relationship. At most, this
study could show that a relationship existed,
after the fact, between the quality of teacher
preparation and subsequent teacher effectiveness.
Where a strong relationship is found between
the independent and dependent variables, three
possible interpretations are open to the researcher:
that the variable X has caused O.
that the variable O has caused X
that some third unidentified, and therefore
unmeasured, variable has caused X and O.
It is often the case that a researcher cannot tell
which of these is correct.
The value of co-relational or causal studies lies
chiefly in their exploratory or suggestive character
for, as we have seen, while they are not always
adequate in themselves for establishing causal
relationships among variables, they are a useful
first step in this direction in that they do yield
measures of association.
In the criterion-group (or causal-comparative)
approach, the investigator sets out to discover
possible causes for a phenomenon being studied,
by comparing the subjects in which the variable is
present with similar subjects in whom it is absent.
The basic design in this kind of study may be
represented thus:
X
O 1
O 2
If, for example, a researcher chose such a design
to investigate factors contributing to teacher
effectiveness, the criterion group O 1 the effective
teachers, and its counterpart O 2 , a group not
showing the characteristics of the criterion group,
are identified by measuring the differential effects
of the groups on classes of children. The researcher
may then examine X, some variable or event, such
as the background, training, skills and personality
of the groups, to discover what might ‘cause’ only
some teachers to be effective.
Criterion-group or causal-comparative studies
may be seen as bridging the gap between
descriptive research methods on the one hand
and true experimental research on the other.
Characteristics of ex post facto research
In ex post facto research the researcher takes
the effect (or dependent variable) and examines
the data retrospectively to establish causes,
relationships or associations, and their meanings.
Other characteristics of ex post facto research
become apparent when it is contrasted with true
experimental research. Kerlinger (1970) describes
the modus operandi of the experimental researcher.
(‘If x, then y’ in Kerlinger’s (1970) usage. We
have substituted X for x and O for y to
fit in with Campbell’s and Stanley’s (1963)
conventions throughout the chapter.) Kerlinger
(1970) hypothesizes: if X, thenO; iffrustration,
then aggression. Depending on circumstances and
his own predilections in research design, he uses
some method to manipulate X. He then observes
O to see if concomitant variation, the variation
expected or predicted from the variation in X,
occurs. If it does, this is evidence for the validity of
the proposition, X-O,meaning‘IfX,thenO’. Note
that the scientist here predicts from a controlled
X to O. Tohelphimachievecontrol,hecan
use the principle of randomization and active
manipulation of X and can assume, other things
being equal, that O is varying as a result of the
manipulation of X.
In ex post facto designs, on the other hand, O is
observed. Then a retrospective search for X ensues.
An X is found that is plausible and agrees with