| smean.sd {Hmisc} | R Documentation |
A number of statistical summary functions is provided for use
with summary.formula and summarize (as well as
tapply and by themselves).
smean.cl.normal computes 3 summary variables: the sample mean and
lower and upper Gaussian confidence limits based on the t-distribution.
smean.sd computes the mean and standard deviation.
smean.sdl computes the mean plus or minus a constant times the
standard deviation.
smean.cl.boot is a very fast implementation of the basic
nonparametric bootstrap for obtaining confidence limits for the
population mean without assuming normality.
These functions all delete NAs automatically.
smedian.hilow computes the sample median and a selected pair of
outer quantiles having equal tail areas.
smean.cl.normal(x, mult=qt((1+conf.int)/2,n-1), conf.int=.95, na.rm=TRUE) smean.sd(x, na.rm=TRUE) smean.sdl(x, mult=2, na.rm=TRUE) smean.cl.boot(x, conf.int=.95, B=1000, na.rm=TRUE, reps=FALSE) smedian.hilow(x, conf.int=.95, na.rm=TRUE)
x |
for summary functions smean.*, smedian.hilow, a numeric vector
from which NAs will be removed automatically
|
na.rm |
defaults to TRUE unlike built-in S-Plus functions, so that by
default NAs are automatically removed
|
mult |
for smean.cl.normal is the multiplier of the standard error of the
mean to use in obtaining confidence limits of the population mean
(default is appropriate quantile of the t distribution). For
smean.sdl, mult is the multiplier of the standard deviation used
in obtaining a coverage interval about the sample mean. The default
is mult=2 to use plus or minus 2 standard deviations.
|
conf.int |
for smean.cl.normal and smean.cl.boot specifies the confidence
level (0-1) for interval estimation of the population mean. For
smedian.hilow, conf.int is the coverage probability the outer
quantiles should target. When the default, 0.95, is used, the lower
and upper quantiles computed are 0.025 and 0.975.
|
B |
number of bootstrap resamples for smean.cl.boot
|
reps |
set to TRUE to have smean.cl.boot return the vector of bootstrapped
means as the reps attribute of the returned object
|
a vector of summary statistics
Frank Harrell
Department of Biostatistics
Vanderbilt University
f.harrell@vanderbilt.edu
set.seed(1) x <- rnorm(100) smean.sd(x) smean.sdl(x) smean.cl.normal(x) smean.cl.boot(x) smedian.hilow(x, conf.int=.5) # 25th and 75th percentiles