To use a more psychological example, let’s look at a depression scale (Bollen and Lennox used the CES-D, but here I have used the Interval General Health Questionnaire; Surtees and Miller, 1990).
Being unhappy and depressed looks like it is an effect of depression, but having restless and disturbed nights could be an effect of depression, or alternatively it might be a cause of depression. Finally, finding everything getting on top of you could be an effect of depression, or it might be a cause.
