Ex post facto research

Introduction

When translated literally, ex post facto means 'from what is done afterwards'. In the context of social and
educational research the phrase means ‘after the fact’ or ‘retrospectively’ and refers to those studies which
investigate possible cause-and-effect relationships by observing an existing condition or state of affairs and
searching back in time for plausible causal factors. In effect, researchers ask themselves what factors seem
to be associated with certain occurrences, or conditions, or aspects of behaviour.

Ex post facto Research, then, is a method of teasing out possible antecedents of events that have happened.
and cannot, therefore, be engineered or manipulated by the investigator.

The following example will illustrate the basic idea.

• Imagine a situation in which there has been a dramatic increase in the number of fatal road accidents.
in a particular locality. An expert is called in to investigate. Naturally, there is no way in which she can
study the actual accidents because they have happened; nor can she turn to technology for a video
replay of the incidents. What she can do, however, is attempt a reconstruction by studying the
statistics, examining the accident spots, and taking note of the statements given by victims and
In this way the expert will be in a position to identify possible determinants of the accidents.
These may include excessive speed, poor road conditions, careless driving, frustration, inefficient
vehicles, the effects of drugs or alcohol and so on. Based on her examination, she can formulate
hypotheses as to the likely causes and submit them to the appropriate authority in the form of
recommendations. These may include improving road conditions or lowering the speed limit.
or increasing police surveillance, for instance. The point of interest to us is that in identifying the
causes retrospectively, the expert adopts an ex post facto perspective.

Kerlinger (1970) has defined

ex post facto research more formally as that in which the independent variable or variables have already
occurred and in which the researcher starts with the observation of a dependent variable or variables. She
then studies the independent variable or variables in retrospect for their possible relationship to, and effects
on, the dependent variable or variables. The researcher is thus examining retrospectively the effects of a
naturally occurring event on a subsequent outcome with a view
to establishing a causal link between them. Interestingly, some instances of ex post facto designs
correspond to experimental research in reverse, for instead of taking groups that are equivalent and
subjecting them to different treatments in order to bring about differences in the dependent variables to be
measured, an ex post facto experiment begins with groups that are already different in some respect and
searches in retrospect for the factor that brought about the difference.

Indeed, Spector (1993:42) suggests that ex post facto research is a procedure that is intended to transform a
non-experimental research design into a pseudo-experimental form.

Two kinds of design may be identified in ex post facto research.

 1.co-relational study or causal research

Causal Research, as explained byDJS Research Ltd.

Causal Research explores the effect of one thing on another and more specifically, the effect of one variable on
another.

The research is used to measure what impact a specific change will have on existing norms and allows market.
Researchers to predict hypothetical scenarios upon which a company can base its business plan.

For example, if a clothing company currently sells blue denim jeans, causal research can measure the impact of the
company changing the product design to the colour white.

Following the research, company bosses will be able to decide whether changing the colour of the jeans to white would
be profitable.

To summarize, causal research is a way of seeing how actions now will affect a business in the future.

2. criterion group study or 'causal-comparative research'.

Ex Post Facto Research Method

Ex post facto means formulated, enacted, or operating retroactively. When translated literally, ex post facto
means from what is done afterwards. In social and educational research, the phrase means: after the fact. Ex
Post facto research method refers to those studies which investigate possible cause-and-effect relationships.
by observing an existing condition or state of affairs and looking back in time for valid causal factors. The ex
The post facto research method is a method of using statistics and alternative ways to figure out an event.
One would not be able to study actual events because they have already happened. Go to for further detailed
information.

Ex Post Facto (Causal-Comparative) Research

Explores possible causes and effects. The independent variable is not manipulated; it has already been.
applied Focuses first on the effect, then attempts to determine what caused the observed effect.

Characteristics of Ex Post Facto Research

• There is a control or comparison group

• Intact groups are used
• The treatment is not manipulated, it has already occurred.

EX POST FACTO - Term used to designate action taken to change the effect given to a set of circumstances.
This action relates back to a prior time and places this new effect upon the same set of circumstances.
existing at that time.
EX POST FACTO RESEARCH

Definition

Literally,

ex post facto means 'from what is done afterwards'. In the context of educational research, this
The phrase means 'after the fact' or 'retrospectively' and refers to those studies which investigate
possible cause-and-effect relationship by observing an existing condition or state of affairs
and searching back in time for plausible causal factors.

after the fact

research is a method of teasing out possible antecedents of events that happened and
cannot, because of
this effect can be engineered or manipulated by the investigator. More formally, it can be
defined as a research in which the
Independent variable or variables have already occurred and the researcher starts with
observation of a dependent variable or variables. In this case, the researcher then
studies the independent variable or variables in retrospect for their possible relationship
to, and effects on, the dependent variable or variables. Thus, the researcher is
examining retrospectively the effects of naturally occurring events on subsequent
outcome with a view to establishing a causal link between them.

Kinds of Design in Ex Post Facto Research

There are two kinds of design in ex post facto research, they

1. Correlational study (causal research) is concerned with identifying the
antecedents of a present condition. The basic design is: This design has three possible
interpretations: a. that the variable X has caused Ob. that the variable O has
caused X, or that some third unidentified, and therefore unmeasured, variable has
caused X and O2. Criterion group study (causal comparative research) is concerned
with the attempts to discover possible causes for the phenomenon being studied by
comparing the subjects in which the variable is present with similar subjects in whom
it is absent. This approach is seen as bridging the gap between
descriptive research method on the one hand and true experimental research on the
other hand. The basic design of this study is:

X
Characteristic of Ex Post Facto Research

data are collected after the presumed cause or causes have occurred
with true experimental research, in EPF the manipulation control and randomization
of the independent variable is not possible The advantages of EPF are (1) it is
appropriate when the more powerful experiment method is not possible; (2) it can
yield useful information concerning the nature of phenomena; (3) improvement in
statistical technique and general methodology have made this design more
defensible; (4) it is appropriate when simple cause-and-effect relationships are being
explored; (5) the method can give a sense of direction and provide a fruitful source
of hypothesis
that can be tested by the more rigorous experimental methods subsequently.
SOURCES

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