Class | Analysis and data manipulation command |
Name | kendalltau |
Arguments | <age-at-onset> <censor> [<zygosity_score> even | odd | (>|>=|<|<=|==|^= <threshold>)] |
For all pairs of twins or siblings from each twin zygosity group, calculate Oakes's version of Kendall's tau for right censored data.
If a gamma frailty model fits the data, the estimator is unbiased in the presence of censoring [Oakes 2008], and,
tau = (OR-1)/(OR+1) ,
where OR is the continuation odds ratio,
OR = S11S00 / (S10S01)
with Sij is (d/dt)i (d/dt)j S(t1,t2), and S(t1, t2) the bivariate survivor function. In the Clayton-Cuzick bivariate survival model, OR is constant at all (pairs of) ages.
Example:
>> # >> # Cable insulation failure data used as an example by Oakes 1986 >> # S is the time to inception of the fault, and T the subsequent >> # time to failure >> # Oakes, D. A model for bivariate survival data. >> # In Moolgavkar, S.H. and Prentice, R.L. (Eds.) >> # Modern Statistical Methods in Chronic Disease >> # Epidemiology, Wiley, New York, pp. 151-166, 1986 >> # >> set loc zyg qua >> set loc type qua >> set loc time qua >> read pedigree inline >> 1 S 1 2 x 1 0 228 >> 1 T 1 2 x 1 1 30 >> 2 S 1 2 x 1 0 106 >> 2 T 1 2 x 1 1 8 >> 3 S 1 2 x 1 0 246 >> 3 T 1 2 x 1 1 66 >> 4 S 1 2 x 1 0 700 >> 4 T 1 2 x 1 1 72 >> 5 S 1 2 x 1 0 473 >> 5 T 1 2 x 1 1 25 >> 6 S 1 2 x 1 0 155 >> 6 T 1 2 x 1 1 7 >> 7 S 1 2 x 1 0 414 >> 7 T 1 2 x 1 1 30 >> 8 S 1 2 x 1 0 1374 >> 8 T 1 2 x 1 1 90 >> 9 S 1 2 x 1 0 1227 >> 9 T 1 2 x 1 1 39 >> 10 S 1 2 x 1 0 254 >> 10 T 1 2 x 1 1 46 >> 11 S 1 2 x 1 0 435 >> 11 T 1 2 x 1 1 85 >> 12 S 1 2 x 1 0 1155 >> 12 T 1 2 x 1 1 85 >> 13 S 1 2 x 1 0 195 >> 13 T 1 2 x 1 1 27 >> 14 S 1 2 x 1 0 117 >> 14 T 1 2 x 1 1 27 >> 15 S 1 2 x 1 0 724 >> 15 T 1 2 x 1 1 21 >> 16 S 1 2 x 1 0 300 >> 16 T 1 2 x 1 1 96 >> 17 S 1 2 x 1 0 128 >> 17 T 1 2 x 1 1 4 >> ;;;; >> run >> set loc dummy aff >> dummy = y >> set twi zyg >> ken time dummy -------------------------------------------------------------- Twin survival analysis of "time" for outcome "dummy" -------------------------------------------------------------- Zygosity group Pairs Conc Disc Tau OR Tau(n) OR(n) --------------- ------ ---- ----- ------ -------- ------ -------- MZ twins 17 96 37 0.4338 2.53 0.4436 2.59 DZ twins 0 0 0 0.0000 1.00 0.0000 1.00 Sibs (non-MZ) 0 0 0 0.0000 1.00 0.0000 1.00
See also:
twin | classical twin analysis |
kaplan-meier | univariate survivor function estimate |
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