Does the month in which you were born relate to your later mental health? Fombonne

(1989) took all children referred to a psychiatric clinic in Paris with a diagnosis of psychosis and sorted them by birth month. (There were 208 such children.) He had a control group of 1,040 children referred with other problems. The data are given below, along with the percentage in the general population born in that month.

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Total Psychosis 13 12 16 18 21 18 15 14 13 19 21 28 208 Control 83 71 88 114 86 93 87 70 83 80 97 88 1040 % General Population 8.4 7.8 8.7 8.6 9.1 8.5 8.7 8.3 8.1 8.1 7.6 8.0

(a) How will you adjust (transform) the Psychosis and Control groups’ data so that all three data sets can fit on the same graph?

(b) How will you plot the data?

(c) Plot the data.

(d) Do those diagnosed with psychosis appear to differ from the general population?

(e) What purpose does the Control group play?
(f ) What do you conclude?