Experimental and ex post facto designs – UGC NET Question

Statement B is the only wrong statement because ex post facto research does not randomly assign participants to treatment and control groups; it studies groups that already differ on the variable of interest. Statements A, C, D and E correctly distinguish experimental designs from ex post facto designs. Experimental work manipulates the independent variable and controls extraneous factors, whereas ex post facto designs rely on existing differences and require cautious causal interpretation. The phrase “after the fact” correctly captures that the critical events have already occurred in ex post facto research.

Option A:
Option A is correct because it identifies B alone as the wrong statement and leaves A, C, D and E as correct descriptions. It acknowledges that random assignment is a feature of true experiments, not ex post facto designs, and correctly treats all other statements as conceptually sound.

Option B:
Option B is incorrect because it treats A as if it were also wrong, even though A correctly characterises experimental research as involving manipulation and control. By misclassifying a true statement as wrong, this option fails to isolate the actual source of error.

Option C:
Option C wrongly groups D with B, even though D correctly notes that causal claims from ex post facto studies must be cautious. While B is indeed false, D is a prudent caution and should not be listed as wrong, so this option presents an inaccurate combination.

Option D:
Option D adds E to B as if both were wrong, but E accurately explains the meaning of “after the fact” in ex post facto research. Because it treats a true explanatory statement as incorrect, this option cannot be accepted.

Option E is also incorrect because it includes A and C, both of which are true, among the wrong statements. This shows confusion between features of experiments and ex post facto designs and leads to an invalid set of “wrong” statements.