Table 2.
Sample Sizes and Response Rates (%) for Sibling Pairs by Type of Genetic Relatedness and Wave of Data Collection.
| Sibling Pair Type |
Wave I 1995 |
Wave II 1996 |
Wave II Response Rate† |
Wave III 2001-02 |
Wave III Response Rate† |
Wave IV 2008-09 |
Wave IV Response Rate† |
|---|---|---|---|---|---|---|---|
| MZ twins | 307 | 283 | 92.8 | 273 | 89.5 | 282 | 92.5 |
| DZ Twins | 452 | 425 | 94.0 | 401 | 89.1 | 418 | 92.7 |
| Full-Siblings | 1251 | 1182 | 94.6 | 1151 | 92.4 | 1173 | 93.9 |
| Half-Siblings | 442 | 432 | 98.0 | 384 | 86.9 | 399 | 90.3 |
| Unrelated | 662 | 630 | 95.2 | 576 | 87.4 | 611 | 92.3 |
| Total | 3114 | 2976 | 94.9 | 2804 | 90.1 | 2883 | 92.7 |
†
Response rates are based on the following denominator and numerator: a pair was considered eligible if one member met the requirements for interview selection (note this eligibility changes over waves due to death or overseas location); only one member of the pair needed to be interviewed for the pair to be included in response category.