Stata 15 help for st_forceshared


[ST] stcox, forceshared -- Force estimation of a shared-frailty survival model


stcox ... , forceshared ...

streg ... , forceshared ...


stcox, forceshared and streg, forceshared force estimation of shared-frailty survival models in the presence of delayed entries or gaps.


You can use the shared() option to fit a shared-frailty survival model with stcox or streg. This option is not allowed in the presence of delayed entries or gaps. You may override this by specifying the forceshared option, but we do not recommend this. If you use forceshared, you will obtain consistent results only under the assumption that the frailty distribution in the sample is independent of the covariates and the truncation points. This is a restrictive assumption, and you should evaluate whether it is reasonable for your data before you proceed with estimation. For more information, see van den Berg and Drepper (2011), which prompted the change in the behavior of the shared() option.


van den Berg, G. J., and B. Drepper. 2011. Inference for shared-frailty survival models with left-truncated data. Discussion Paper series. Forschungsinstitut zur Zukunft der Arbeit, No. 6031, urn:nbn:de:101:1-201110263752.

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