EX POST FACTO DESIGN

Ex-post facto research measures the relationship between two variables without manipulating the X-variables. While the experimental research starts from manipulating and controlling the independent X-variables and proceeds to observing the effect on the dependent variables, the Ex-Post Facto Research starts from identifying the existing conditions in x-variable (e.g., sex) and proceeds to finding the differences in Y- variable. If we observe that the students in a language department are dominated by female students, then we may conduct an Ex-post facto research to find out whether sex differences relate to different results in achievement. If we observe that most of the freshmen of the English Department graduating from State Senior High School achieve English skills better than those graduating from Private Senior High Schools, then we may want to conduct an Ex-post facto research to find out whether different high school backgrounds of the students show different students’ achievement in learning English skills.

This research design is also called Causal Comparative Research involving both continuous as well as discrete variables for the x-variables that have :

1.      Inherent characteristics (organismic) e.g., gender, ethnicity, personality traits

2.      Characteristics that should not be manipulated for ethical reasons, e.g., illegal drug use, cigarette smoking, or alcohol consumption,

3.      Characteristics that could be manipulated but that are not, e.g., school placement, social promotion to the next grade, or participation in psycho-therapy.

With discrete variables, causal comparative research design can be used to investigate the different academic achievements between male students and female students (x-sex variable), between Javanese students and Chinese students (x-ethnicity variable), between moslem female students and non moslem female students (x-religion variable), between students whose parents are school teachers or university lecturers and those whose parents are not school teachers or university lecturers (x-parents’ profession variables)

With continuous variables, causal Comparative research can be used to investigate the different academic achievements between students with high intelligence and low intelligence, between students from high socioeconomic background and low high socioeconomic background, between students whose parents are university graduates and those whose parents are high school graduates, etc.

Although the conclusions in Ex-post Facto Research or Causal Comparative Research show significant differences in the level of x-variables (e.g., a group of students with high self-concepts achieve significantly higher in their academic achievement than those with low self-concepts, a group of students whose parents are school teachers or university lecturers than those whose parents are not school teachers, a group of freshmen of the English Department graduating from state senior high schools semester English Intensive Course than those graduating from private senior high schools), since the research does not involve experimental manipulation of x-variables, the significance differences in the level of x-variables do not show confident proof of a cause-and-effect relationship.

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