aftreg {eha} | R Documentation |
The accelerated failure time model with parametric baseline hazard(s). Allows for stratification with different scale and shape in each stratum, and left truncated and right censored data.
aftreg(formula = formula(data), data = parent.frame(), na.action = getOption("na.action"), dist = "weibull", init, shape = 0, control = list(eps = 1e-08, maxiter = 20, trace = FALSE), singular.ok = TRUE, model = FALSE, x = FALSE, y = TRUE)
formula |
a formula object, with the response on the left of a ~ operator, and the terms on the right. The response must be a survival object as returned by the Surv function. |
data |
a data.frame in which to interpret the variables named in the formula. |
na.action |
a missing-data filter function, applied to the
model.frame, after any subset argument has been used.
Default is options()$na.action . |
dist |
Which distributin? Default is "weibull", with the
alternatives "gompertz", "ev", "loglogistic" and "lognormal". A special
case like the exponential can be obtained by choosing "weibull"
in combination with shape = 1 . |
init |
vector of initial values of the iteration. Default initial value is zero for all variables. |
shape |
If positive, the shape parameter is fixed at that value. If zero or negative, the shape parameter is estimated. Stratitfication is not meaningful if shape is fixed. |
control |
a list with components eps (convergence
criterion), maxiter (maximum number of iterations), and
silent (logical, controlling amount of output). You can
change any component without mention the other(s). |
singular.ok |
Not used. |
model |
Not used. |
x |
Return the design matrix in the model object? |
y |
Return the response in the model object? |
The parameterization is different
from the one used by survreg
.
The model is
S(t; a, b, beta, z) = S_0((t/exp(b - z beta))^a)
where S_0 is some standardized survivor function.
A list of class c("aftreg", "coxreg", "coxph")
with components
coefficients |
Fitted parameter estimates. |
var |
Covariance matrix of the estimates. |
loglik |
Vector of length two; first component is the value at the initial parameter values, the second componet is the maximized value. |
score |
The score test statistic (at the initial value). |
linear.predictors |
The estimated linear predictors. |
means |
Means of the columns of the design matrix. |
w.means |
Weighted (against exposure time) means of covariates; weighted relative frequencies of levels of factors. |
n |
Number of spells in indata (possibly after removal of cases with NA's). |
events |
Number of events in data. |
terms |
Used by extractor functions. |
assign |
Used by extractor functions. |
y |
The Surv vector. |
isF |
Logical vector indicating the covariates that are factors. |
covars |
The covariates. |
ttr |
Total Time at Risk. |
levels |
List of levels of factors. |
formula |
The calling formula. |
call |
The call. |
method |
The method. |
convergence |
Did the optimization converge? |
fail |
Did the optimization fail? (Is NULL if not). |
pfixed |
TRUE if shape was fixed in the estimation. |
The print method print.aftreg
doesn't work if
threeway or higher order interactions are present. Use
print.coxph
in that case.
Göran Broström
data(male.mortality) aftreg(Surv(enter, exit, event) ~ ses, data = male.mortality, dist = "gompertz") phreg(Surv(enter, exit, event) ~ ses, data = male.mortality, dist = "gompertz") coxreg(Surv(enter, exit, event) ~ ses, data = male.mortality)