This page contains only historical information and is not about the current
release of Stata.
Please see our Stata 13 page
for information on the current version of Stata.
Existing estimation commands stcox and
streg may now be used with the
svy: prefix and so can fit models for complex survey data; see [ST]
stcox and [ST]
New command stpower provides sample-size and
power calculations for survival studies that use Cox proportional hazards
regressions, log-rank tests for two groups, or differences in
exponentially distributed hazards or log hazards.
The stpower commands allow automated production
of customizable tables and have options to assist with creating graphs of
power curves. See [ST]
stpower cox estimates required sample size
(given power) or power (given sample size) or the minimal detectable
coefficient (given power and sample size) for models with multiple
covariates. The command provides options to account for possible
correlation between the covariate of interest and other predictors and
for withdrawal of subjects from the study. See [ST]
stpower logrank estimates required sample
size (given power) or power (given sample size) or the minimal
detectable hazard ratio (given power and sample size) for studies
comparing survivor functions of two groups by using the log-rank
test. Both the Freedman (1982) and the Schoenfeld (1981) methods are
provided. The command allows for unequal allocation of subjects
between the groups and possible withdrawal of subjects. Estimates can
be adjusted for uniform accrual. See [ST]
stpower exponential estimates sample size
(given power) or power (given sample size) of tests of the difference
between hazards or log hazards of two groups under the assumption of
exponential survivor functions (also known as the exponential test).
Both the Lachin–Foulkes and Rubinstein–Gail–Santner
methods are provided. Unequal group allocation, uniform or truncated
exponential accrual, and different exponential losses due to follow-up
in each group are allowed. See [ST]
Concerning existing command sts graph,
See [ST] sts
version to less than 10 restores previous behavior.
New option risktable() places a
subjects-at-risk table underneath and aligned to the survival or
New option ci replaces old options
gwood, cna, and
cihazard. sts graph
will choose the appropriate confidence interval on the basis of the
function being graphed.
Confidence intervals are now graphed using shaded areas, and new
options plotopts() and
ciopts() allow you to control how plots and confidence
New option censopts() controls the
appearance of ticks and markers produced by existing option
Boundary computations for smoothing hazards have been improved. New
option noboundary specifies that no boundary
correction be done.
The lower bound of the range to plot the hazard function now extends
Option na has been renamed
cumhaz. na may
still be used.
For sts list,
option na has been renamed
na may be used as a synonym for
stcurve analogous to those of
have been made.
- Boundary computations for smoothing hazards have been improved.
New option noboundary specifies that no
boundary correction be done.
- The lower bound of the range to plot the hazard function now
extends to zero.
All st estimation commands accept option
As mentioned in More new statistical features,
are the right ways to specify the old robust and
cluster() options, and vce()
now allows other VCE calculations as well.
Existing command predict after
stcox has a new option,
scores, that allows generating variables with the
partial coefficient score residuals; see [ST]
Existing command ltable has new options
ci#opts() that allow for
more customization of the graph. New option ci
adds confidence intervals to the graph. See [ST]
Existing command stphplot has a new option
allows for most customizations of the graph. See [ST]
Existing command stcoxkm has new options
that allow for most customizations of the graph. See [ST]
Existing command cc has new option
tarone that produces Tarone’s (1985)
adjustment of the Breslow–Day test for homogeneity test of odds
ratios. See [ST]
Existing command stdes has been renamed to
continues to work. See [ST]
The [ST] manual has an expanded glossary.
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