A comparison of written and postbox forms of the Leyton Obsessional Inventory.

Two groups of medical students answered a modified version of the Leyton Obsessional Inventory twice, with 8 weeks between tests. On one occasion it was administered in its original card-sorting (postbox) form; on the other, it was given as a written questionnaire. Fifty students answered the postbox form first, 50 the questionnaire first. Correlation between the 2 tests was reasonably good (r = 0.73-0.77). Scores on the first occasion of testing were significantly higher than on the second, but differences between scores on the 2 forms were not significant. Mean scores of male and female students were similar.