Question

Between February and May 1984, investigators identified 50 hospitalized children in 11 states with a confirmed diagnosis of Reye’s syndrome who had a viral illness before admission.  150 controls were identified as children of the same age range who had experienced a similar viral illness during the same period and were treated at the same hospital or emergency room or were part of the same community as the cases but did not have a diagnosis of Reye’s syndrome.  Preliminary results from the study reported that of the 50 children with Reye’s syndrome, 45 had ingested salicylates (aspirin) during their viral illness and 55 of the controls had done so.

1. Construct a 2x2 table and calculate the correct measure of association for this study.

Suppose now that the study was constructed as following 100 children with viral illness who ingested salicylates and 100 children with viral illness who did not ingest salicylates between February and May 1984. Of the 100 children who ingested salicylates (aspirin), 45 had confirmed Reye’s syndrome. Of the 100 children who did not ingest salicylates, 5 had confirmed Reye’s syndrome.

2. Calculate and interpret the correct measure of association for this study

Answer 1

1) Consider two attributes

A : Children with viral illness injected aspirin.

B : confirmed Reye's Syndrome.

( A) = Number of children with illness injected aspirin = 100

( ) = number of children with illness did not inject aspirin. = 100

(AB) = number of children who injected aspirin had confirmed Reye's syndrome = 45

( B ) = number of children who did not injected aspirin had confirmed Reye's syndrome = 5

Hence 2 * 2 contigency table is

Attributes	A		Total
B	45	5	50
	55	95	150
Total	100	100	200

2) Yule's coefficient of association is

Interpretation : Since the value of Q is 0.8791 ( positive). Hence there is positive association between Children with viral illness injected aspirin and had confermed Reye's syndrome.