.- help for ^stselpre^ [ec] Feb 10, 2010 .- Fits proportional hazards model to case-cohort data --------------------------------------------------- ^stselpre^ varlist [^if^ exp] [^in^ range] [^, nohr^ ^l^evel^(^#^)^ ^self^ {^bre^slow | ^efr^on | ^exactm^ | ^exactp^} ^nosh^ow ^force^ ] ^stselpre^ is for use with survival-time data; see help @st@. Before using the command, data must be prepared for case-cohort analysis by ^stcascoh^; see help @stcascoh@. Description ----------- ^stselpre^ returns estimates and standard errors from proportional hazards fit to case-cohort data. Coefficients are estimated according to two methods: - Self-Prentice scheme. Risk sets uses just the sub-cohort member at risk, - Prentice scheme. Risk sets are augmented by non sub-cohort cases when they fail. The asymptotic Self-Prentice method variance-covariance matrix and standard errors are computed using the simplification described in Therneau and Li (1999). The syntax of @predict@ following ^stselpre^ is as in ^stcox^ Options ------- ^nohr^ specifies that coefficients rather than hazard ratios are to be displayed ^nohr^ may be typed at estimation or when replaying previously estimated results. ^level(^#^)^ specifies the confidence level for the confidence intervals of the coefficients; see help @level@. ^level^ may be also specified when replaying previously estimated results. ^self^ specifies that Self-Prentice method coefficient vector is to be saved in e(b). Prentice method coefficients are saved by default. ^breslow^, ^efron^, ^exactm^, and ^exactp^ each specify a method for handling tied deaths that the underlying ^stcox^ command executes. ^efron^ is the default. ^noshow^ prevents ^stselpre^ from displaying the identities of the key st variables above its output. ^force^ prevents ^stselpre^ from doing some check on the data set previously prepared by ^stcascoh^. Examples -------- . ^stselpre stage age^ . ^xi: stselpre i.stage*i.histol, nohr self^ Also see -------- Manual: ^[R] stcox [R] sttocc^ On-line: help for @stcascoh@ @stcox@ @sttocc@ Reference --------- Therneau M T, Li H: Computing the Cox Model for Case Cohort Designs. Lifetime Data Analysis 1999; 5: 99-112. Author ------ Enzo Coviello Epidemiology Unit ASL BT Italy enzo.coviello@@alice.it