In a study of concordance, a sample of identical twins was evaluated for adult-onset diabetes. The data below were collected for this trait:
1. In 36 identical twin pairs, both showed adult-onset diabetes.
2. In 40 identical twin pairs, only one showed adult-onset diabetes.
3. In 336 identical twin pairs, neither showed adult-onset diabetes.
Items 1 and 2 can be used to calculate concordance for identical twins as follows: 36/(36 + 40) × 100 = 47%.

Question

Quizplus · Accepted Answer

The concordance rate is calculated by dividing the number of twin pairs where both twins exhibit the trait (in this case, adult-onset diabetes) by the total number of twin pairs where at least one twin exhibits the trait, then multiplying by 100 to get a percentage. Here, 36 pairs both have diabetes out of 76 pairs where at least one has it (36 with both + 40 with one), resulting in a concordance rate of 47%.

In a Study of Concordance, a Sample of Identical Twins