Ex Post Facto research l Researcher cannot manipulate
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Ex Post Facto research l Researcher cannot manipulate some variables and therefor selects participants that have certain values for those variables by themselves (gender, personality, illness, . . . ) Pros Cons • Often only possible approach • Selection threat to internal validity: probably not only independent variable differs among participants 1
Ex Post Facto - example Depression in rape victims 2
Research design X 1 = rape victim X 2 = control Yij = average depression score in group i, at time j ---- indicates possible unequality of groups in both conditions 3
Generations Longitudinal design Timespan of research TIME 4
Assess evolution from longitudinal study Comparison of successive measures of Yi • Experimental loss • Cost • Insensitive to cohort effects 5
Generations Cross-sectional research Timespan of research TIME 6
Assess evolution from cross-sectional study Comparing different measures of Yi(from different groups) • No experimental loss • Fast and cheap • Cohort effects occur but cannot be assessed 7
Generations Cohort-sequential research Timespan of research TIME 8
Assess evolution from cohorte-sequential study Yij = measure at time i in participants of age j Evolution within cohort is assessed from successive measures Yij Evolution between cohorts (apart from age) is assessed from comparison between Y 1 N and Y 2 N • Experimental loss • Cost • Cohort effects can be assessed 9
Longitudinal <> Cross-sectional research Intelligence and age Average IQ l a Longitudin Cross-sec ti onal Age 10
Ex facto research
De facto research
Diseños ex post facto
Penelitian ex post facto kualitatif
Ex post facto design
Connecticut compromise
Investigación ex post facto ejemplos
If you can not measure it you can not improve it
The supernatural soliciting cannot be ill cannot be good
If you don't measure it you can't manage it
If you can't measure it, you can't manage it
