Table 5.
ANOVA-based heritability estimates of heart rate response to arousal measures in MZ and DZ twinsa.
| Measures | Within pair average value | Total variance | Heritability estimate | |||
|---|---|---|---|---|---|---|
| F-testb | T-testc | F-testb | ||||
| p | p | p | H2 | pd | Type | |
| Arousal index | .530 | .519 | .730 | 0.307 | .129 | WP |
| Average arousal duration | .416 | .395 | .798 | 0.460 | .117 | WP |
| Average arousal intensity scale | .535 | .333 | .507 | 1.127 | <.001 | WP |
| Slope of ΔHR per arousal intensity | .124 | .074 | .065 | −0.605 | .898 | AmCo |
| Arousal intensity threshold of ΔHR | .170 | .702 | .831 | 1.237 | .002 | WP |
| Average ΔHR | .293 | .066 | .074 | −0.248 | .695 | AmCo |
| ΔHR at arousal intensity scale 4 | .821 | .090 | .600 | 0.240 | .165 | WP |
| ΔHR at arousal intensity scale 5 | .447 | .063 | .334 | 0.085 | .348 | WP |
| ΔHR at arousal intensity scale 8 | .168 | .051 | .117 | −0.662 | .911 | AmCo |
aHeritability estimates using analysis of variance (ANOVA)-based variance formulas for within pairs (WP) or among component (AmCo) heritability. The WP estimate is most valid when the total variance F-test has a p>.20, and calculated as H2 = [2 • (MSWDZ - MSWMZ)] / [(MSAMZ + MSWDZ + MSADZ + MSWMZ)/4]. The AmCo estimate is valid when the total variance F-test has a p<.20, and calculated H2 = [(MSAMZ - MSADZ) + (MSWDZ - MSWMZ)] / [(MSAMZ + MSWDZ + MSADZ + MSWMZ)/4]28,29.
bF-test p-value comparing variability in indicated measure between MZ and DZ twins.
cT-test p-value comparing within pair average values in indicated measure between MZ and DZ twins.
done-sided p-values based on F-tests of significance for heritability estimate, using F-ratio = MSWDZ / MSWMZ for WP heritability estimates and an F-ratio = (MSAMZ + MSWDZ) / (MSADZ + MSWMZ) for AmCo heritability estimates. Abbreviations: H2: broad-sense heritability, ΔHR: heart rate response to arousal, WP: within pairs heritability estimate, AmCo: among component heritability estimate.