Abstract
Tests for the presence of heterogeneity in frailty models use an alternative hypothesis in which the heterogeneity parameter is subject to an inequality constraint. As a result, the classical likelihood ratio asymptotic chi-square distribution theory is no longer valid. Our main result states the limiting distribution of the likelihood ratio and score statistic for the one-sided testing problem. The resulting distribution is a mixture of chi-square distributed random variables. The results are shown for gamma and positive stable frailty distributions, and hold when covariate information is present. A data example illustrates the tests. We also assess, in a simulation study, the performance of the tests regarding the significance level and power.
Similar content being viewed by others
References
Bjarnason H, Hougaard P (2000) Fisher information for two gamma frailty bivariate Weibull models. Lifetime Data Anal 6:59–71
Chernoff H (1954) On the distribution of the likelihood ratio. Ann Math Stat 25:573–578
Claeskens G (2004) Restricted likelihood ratio lack-of-fit tests using mixed spline models. J Roy Stat Soc Ser B 66(4):909–926
Clayton D, Cuzick J (1985) Multivariate generalizations of the proportional hazards model. J Roy Stat Soc Ser A 148(2):82–117
Clayton DG (1978) A model for association in bivariate life tables and its application in epidemiological studies of familial tendency in chronic disease incidence. Biometrika 65(1):141–151
Commenges D, Andersen PK (1995) Score test of homogeneity for survival data (with discussions). Lifetime Data Anal 1(2):145–159
Duchateau L, Janssen P, Lindsey P, Legrand C, Nguti R, Sylvester R (2002) The shared frailty model and the power for heterogeneity tests in multicenter trials. Comput Stat Data Anal 40(3):603–620
Feller W (1971) An introduction to probability theory and its applications, vol II, 2nd edn. Wiley, New York
Ferguson TS (1996) A course in large sample theory. Texts in statistical science series. Chapman and Hall, London
Geyer CJ (1994) On the asymptotics of constrained M-estimation. Ann Stat 22(4):1993–2010
Hougaard P (2000) Analysis of multivariate survival data. Statistics for biology and health. Springer, New York
Huster WJ, Brookmeyer R, Self SG (1989) Modelling paired survival data with covariates. Biometrics 45(1):145–156
Maller RA, Zhou X (2003) Testing for individual heterogeneity in parametric models for event-history data. Math Methods Stat 12(3):276–304
Morgan BJT (1992) Analysis of quantal response data. Chapman and Hall, London
Murphy SA (1995) Asymptotic theory for the frailty model. Ann Stat 23(1):182–198
Murphy SA, van der Vaart AW (1997) Semiparametric likelihood ratio inference. Ann Stat 25(4):1471–1509
Robertson T, Wright FT, Dykstra RL (1988) Order restricted statistical inference. Wiley series in probability and mathematical statistics: Probability and mathematical statistics. Wiley, Chichester
Self SG, Liang K-Y (1987) Asymptotic properties of maximum likelihood estimators and likelihood ratio tests under nonstandard conditions. J Am Stat Assoc 82(398):605–610
Sen PK, Silvapulle MJ (2002) An appraisal of some aspects of statistical inference under inequality constraints. J. Stat Plan Inference 107(1–2):3–43
Silvapulle MJ, Silvapulle P (1995) A score test against one-sided alternatives. J Am Stat Assoc 90(429):342–349
Stram DO, Lee JW (1994) Variance components testing in the longitudinal mixed effects models. Biometrics 50:1171–1177
Tawn JA (1988) Bivariate extreme value theory: models and estimation. Biometrika 75(3):397–415
Therneau TM, Grambsch PM (2000) Modeling survival data: Extending the Cox model. Statistics for biology and health. Springer, New York
Vaida F, Xu R (2000) Proportional hazards model with random effects. Stat Med 19:3309–3324
Verbeke G, Molenberghs G (2003) The use of score tests for inference on variance components. Biometrics 59(2):254–262
Vu HTV, Knuiman MW (2002) A hybrid ML-EM algorithm for calculation of maximum likelihood estimates in semiparametric shared frailty models. Comput Stat Data Anal 40(1):173–187
Vu HTV, Zhou S (1997) Generalization of likelihood ratio tests under nonstandard conditions. Ann Stat 25(2):897–916
Author information
Authors and Affiliations
Corresponding author
Rights and permissions
About this article
Cite this article
Claeskens, G., Nguti, R. & Janssen, P. One-sided tests in shared frailty models. TEST 17, 69–82 (2008). https://doi.org/10.1007/s11749-006-0023-9
Received:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s11749-006-0023-9
Keywords
- Inference under inequality constraints
- Frailty models
- Likelihood ratio test
- Mixture of χ 2-distributions
- Score test
- Survival data