Table A1.
MZ Pair Concordance Degree Percentage Distribution, in Standard Deviations
| Within-Pair Differences Percentage, in SDs | Total | |||||
|---|---|---|---|---|---|---|
| 0 | 0-.5 | .5-1 | 1-2 | >2 | ||
| Academic Outcomes | ||||||
| GPA, W1 | 13 | 31 | 35 | 19 | 2 | 100% |
| PPVT, W1 | 10 | 53 | 23 | 13 | 1 | 100% |
| Behavioral & Attitudinal | ||||||
| Substance Use | 61 | -- | 12 | 19 | 8 | 100% |
| Delinquency | 51 | -- | 25 | 19 | 6 | 100% |
| College Aspirations | 69 | -- | 18 | 8 | 5 | 100% |
| College Probability | 58 | -- | 28 | 8 | 6 | 100% |
| No Breakfast | 80 | -- | -- | -- | 20 | 100% |
| Violence | 40 | 25 | 22 | 8 | 5 | 100% |
| School Effort | 68 | -- | -- | -- | 32 | 100% |
| Parental Aspirations | 24 | 23 | 23 | 20 | 11 | 100% |
| Extracurricular Participation | ||||||
| All Clubs | 17 | 28 | 24 | 23 | 8 | 100% |
| Academic Clubs | 36 | 13 | 24 | 19 | 8 | 100% |
| Network Structure | ||||||
| Density | 3 | 29 | 21 | 25 | 22 | 100% |
| Centrality | 6 | 36 | 21 | 25 | 11 | 100% |
| Popularity | 9 | 33 | 26 | 22 | 10 | 100% |
| Network Content | ||||||
| Interactions | 6 | 34 | 25 | 27 | 9 | 100% |
| School Effort | 5 | 28 | 22 | 27 | 18 | 100% |
| School Difficulty | 1 | 29 | 23 | 29 | 18 | 100% |
| Delinquency | 1 | 35 | 23 | 23 | 18 | 100% |
| Race Heterogeneity | 13 | 28 | 22 | 24 | 13 | 100% |
| Age Heterogeneity | 6 | 29 | 23 | 24 | 20 | 100% |
| College Probability | 4 | 33 | 19 | 24 | 21 | 100% |
| Middle Class Probability | 2 | 31 | 23 | 27 | 17 | 100% |
NOTE: These calculations used standard deviations from the full Add Health sample, including twins and non-twins. Numbers in cells are percentages.