Stata 15 help for strate

[ST] strate -- Tabulate failure rates and rate ratios

Syntax

Tabulate failure rates

strate [varlist] [if] [in] [, strate_options]

Calculate rate ratios with the Mantel-Haenszel method

stmh varname [varlist] [if] [in] [, options]

Calculate rate ratios with the Mantel-Cox method

stmc varname [varlist] [if] [in] [, options]

strate_options Description ------------------------------------------------------------------------- Main per(#) units to be used in reported rates smr(varname) use varname as reference-rate variable to calculate SMRs cluster(varname) cluster variable to be used by the jackknife jackknife report jackknife confidence intervals missing include missing values as extra categories level(#) set confidence level; default is level(95) output(filename[,replace]) save summary dataset as filename; use replace to overwrite existing filename nolist suppress listed output graph graph rates against exposure category nowhisker omit confidence intervals from the graph

Plot marker_options change look of markers (color, size, etc.) marker_label_options add marker labels; change look or position cline_options affect rendition of the plotted points

CI plot ciopts(rspike_options) affect rendition of the confidence intervals (whiskers)

Add plots addplot(plot) add other plots to the generated graph

Y axis, X axis, Titles, Legend, Overall twoway_options any options other than by() documented in [G-3] twoway_options -------------------------------------------------------------------------

options Description ------------------------------------------------------------------------- Main by(varlist) tabulate rate ratio on varlist compare(num1,den2) compare categories of exposure variable missing include missing values as extra categories level(#) set confidence level; default is level(95) -------------------------------------------------------------------------

You must stset your data before using strate, stmh, and stmc; see [ST] stset. by is allowed with stmh and stmc; see [D] by. fweights, iweights, and pweights may be specified using stset; see [ST] stset.

Menu

strate

Statistics > Survival analysis > Summary statistics, tests, and tables > Tabulate failure rates and rate ratios

stmh

Statistics > Survival analysis > Summary statistics, tests, and tables > Tabulate Mantel-Haenszel rate ratios

stmc

Statistics > Survival analysis > Summary statistics, tests, and tables > Tabulate Mantel-Cox rate ratios

Description

strate tabulates rates by one or more categorical variables declared in varlist. You can also save an optional summary dataset, which includes event counts and rate denominators, for further analysis or display. The combination of the commands stsplit and strate implements most of, if not all, the functions of the special-purpose person-years programs in widespread use in epidemiology; see [ST] stsplit.

stmh calculates stratified rate ratios and significance tests by using a Mantel-Haenszel-type method.

stmc calculates rate ratios that are stratified finely by time by using the Mantel-Cox method. The corresponding significance test (the log-rank test) is also calculated.

Both stmh and stmc can estimate the failure-rate ratio for two categories of the explanatory variable specified by the first argument of varlist. You can define categories to be compared by specifying them with the compare() option. The remaining variables in varlist before the comma are categorical variables, which are to be "controlled for" using stratification. Strata are defined by cross-classification of these variables.

You can also use stmh and stmc to carry out trend tests for a metric explanatory variable. Here a one-step Newton approximation to the log-linear Poisson regression coefficient is computed.

Options for strate

+------+ ----+ Main +-------------------------------------------------------------

per(#) specifies the units to be used in reported rates. For example, if the analysis time is in years, specifying per(1000) results in rates per 1,000 person-years.

smr(varname) specifies a reference-rate variable. strate then calculates SMRs rather than rates. This option will usually follow using stsplit to separate the follow-up records by age bands and possibly calendar periods.

cluster(varname) defines a categorical variable that indicates clusters of data to be used by the jackknife. If the jackknife option is selected and this option is not specified, the cluster variable is taken as the id variable defined in the st data. Specifying cluster() implies jackknife.

jackknife specifies that jackknife confidence intervals be produced. This is the default if weights were specified when the dataset was stset.

missing specifies that missing values of the explanatory variables be treated as extra categories. The default is to exclude such observations.

level(#) specifies the confidence level, as a percentage, for confidence intervals. The default is level(95) or as set by set level.

output(filename [,replace]) saves a summary dataset in filename. The file contains counts of failures and person-time, rates (or SMRs), confidence limits, and all the categorical variables in the varlist. This dataset could be used for further calculations or simply as input to the table command.

replace specifies that filename be overwritten if it exists. This option is not shown in the dialog box.

nolist suppresses the output. This is used only when saving results to a file specified by output().

graph produces a graph of the rate against the numerical code used for categories of varname.

nowhisker omits the confidence intervals from the graph.

+------+ ----+ Plot +-------------------------------------------------------------

marker_options affect the rendition of markers drawn at the plotted points, including their shape, size, color, and outline; see [G-3] marker_options.

marker_label_options specify if and how the markers are to be labeled; see [G-3] marker_label_options.

cline_options affect whether lines connect the plotted points and the rendition of those lines; see [G-3] cline_options.

+---------+ ----+ CI plot +----------------------------------------------------------

ciopts(rspike_options) affects the rendition of the confidence intervals (whiskers); see [G-3] rspike_options.

+-----------+ ----+ Add plots +--------------------------------------------------------

addplot(plot) provides a way to add other plots to the generated graph; see [G-3] addplot_option.

+-----------------------------------------+ ----+ Y axis, X axis, Titles, Legend, Overall +--------------------------

twoway_options are any of the options documented in [G-3] twoway_options, excluding by(). These include options for titling the graph (see [G-3] title_options) and for saving the graph to disk (see [G-3] saving_option).

Options for stmh and stmc

+------+ ----+ Main +-------------------------------------------------------------

by(varlist) specifies categorical variables by which the rate ratio is to be tabulated.

A separate rate ratio is produced for each category or combination of categories of varlist, and a test for unequal rate ratios (effect modification) is displayed.

compare(num1,den2) specifies the categories of the exposure variable to be compared. The first code defines the numerator categories, and the second code defines the denominator categories.

When compare is absent and there are only two categories, the larger is compared with the smaller; when there are more than two categories, compare analyzes log-linear trend.

missing specifies that missing values of the explanatory variables be treated as extra categories. The default is to exclude such observations.

level(#) specifies the confidence level, as a percentage, for confidence intervals. The default is level(95) or as set by set level.

Examples of strate

Setup . webuse diet

Declare data to be survival-time data . stset dox, origin(time doe) id(id) scale(365.25) fail(fail==1 3 13)

Split the data into ten-year age bands . stsplit ageband, at(40(10)70) after(time=dob) trim

Tabulate failure rates per 1,000 person-years for categories of ageband . strate ageband, per(1000)

Merge reference population dataset with current dataset on ageband . merge m:1 ageband using http://www.stata-press.com/data/r15/smrchd

Obtain SMRs and confidence intervals . strate ageband, per(1000) smr(rate)

Examples of stmh

Setup . webuse diet, clear

Declare data to be survival-time data . stset dox, origin(time dob) enter(time doe) id(id) scale(365.25) fail(fail==1 3 13)

Split the data into ten-year age bands . stsplit ageband, at(40(10)70) after(time=dob) trim

Calculate rate ratio comparing categories of hienergy . stmh hienergy

Calculate rate ratio comparing categories of hienergy by categories of ageband . stmh hienergy, by(ageband)

Compare the effect of hienergy between jobs, controlling for ageband . stmh hienergy ageband, by(job)

Test for trend of heart disease rates with height controlling for ageband . stmh height ageband

Examples of stmc

Setup . webuse diet, clear

stset the data, specifying dob as the origin . stset dox, origin(time dob) enter(time doe) id(id) scale(365.25) fail(fail==1 3 13)

Obtain the effect of high energy controlling for age (time) by stratifying very finely . stmc hienergy

Same as above, but comparing hienergy = 0 versus hienergy = 1 . stmc hienergy, c(0,1)

Stored results

stmh and stmc store the following in r():

Scalars r(RR) overall rate ratio


© Copyright 1996–2018 StataCorp LLC   |   Terms of use   |   Privacy   |   Contact us   |   What's new   |   Site index