Dear Nidhi
Welcome to the group!!
Its a wonderful question.
See primarily research is of 2 types: Descriptive (where we find out the relation between var on the basis of observation of their occurence) and experimental (where we manipulate the data, make one var vary in a range so that we can see its effct iof another var).
In both previous studies exists, review of literature present, hypothesis can be formulated.
Case STudy based research is a type of Descriptive Study while Ex-post facto research resembles to Expt Studies in its approach.
When population is too large, resources are limited, concept is relatively new we try to take 1 unit as case study believing that whatever is applicable in 1 unit is applicable in other similar units.I remember one of my friend worked in year 2000 on SCM in Textile Industries. At that time very few textile companies actually worked on SCM rather never heard of it. So he preferred to choose 1 unit from Birla Group and conducted his study there. This is Case Study method.
Plz read more about it on
https://www.ischool.utexas.edu/~ssoy/usesusers/l391d1b.htmEx post facto
study or after-the-fact research is a category of research design in
which the investigation starts after the fact has occurred without
interference from the researcher. The majority of social research, in
contexts in which it is not possible or acceptable to manipulate the
characteristics of human participants, is based on ex post facto
research designs.
It is also often applied as a substitute for true
experimental research to test hypotheses about cause-and-effect
relationships or in situations in which it is not practical or ethically
acceptable to apply the full protocol of a true experimental design.
Despite studying facts that have already occurred, ex post facto
research shares with experimental research design some of its basic
logic of inquiry. Ex post facto research design does not include any
form of manipulation or measurement before the fact occurs, as is the
case in true experimental designs
Plz share ur opinion and confusion.
Best wishes
Neeraj