The number of samples for the SIMULATE adjustment is set so that the tail area for the simulated is within a certain accuracy radius of with an accuracy confidence of %. The simulation estimates, the true th quantile, where is the value of the ALPHA= simulate-option. SIMULATE Ĭomputes the adjusted p-values from the simulated distribution of the maximum or maximum absolute value of a multivariate normal random vector. Note that ADJUST=TUKEY is incompatible with DIFF=CONTROL. PROC LIFETEST uses the approximation described in Kramer ( 1956) and identifies the adjustment as "Tukey-Kramer" in the results. Performs the paired comparisons based on Tukey’s studentized range test. Performs the paired comparisons based on the studentized maximum modulus test. Performs Scheffé’s multiple-comparison adjustment.Īpplies the idák correction to the raw p-values. PROC LIFETEST uses the factor-analytic covariance approximation described in Hsu ( 1992) and identifies the adjustment in the results as "Dunnett-Hsu." Note that ADJUST=DUNNETT is incompatible with DIFF=ALL. Performs Dunnett’s two-tailed comparisons of the control group with all other groups. The adjustment methods include the following: BONFERRONI BONĪpplies the Bonferroni correction to the raw p-values. See the section Multiple-Comparison Adjustments for mathematical details also see Westfall et al. Specifies the multiple-comparison method for adjusting the p-values of the paired tests. The following list describes these options. Options in the STRATA statement are specified after a slash ("/"). Specifies the type of differences to considerĪllows missing values as valid stratum values Requests a multiple-comparison adjustment Specifies tests corresponding to various weight functions Suppresses printing the test statistic and covariance matrix Specifies the group variable for stratified tests Table 49.2 Options Available in the STRATA Statement Table 49.2 summaries the options available in the STRATA statement. You use the DIFF= option to specify the comparison type, and you use the ADJUST= option to select a method of multiple-comparison adjustments. Two types of paired comparisons can be made: comparisons between all pairs of curves and comparisons between a control curve and all other curves. A multiple-comparison adjustment of the p-values for the paired comparisons retains the same overall false positives as the k-sample test. When comparing more than two survival curves, a k-sample test tells you whether the curves are significantly different from each other, but it does not identify which pairs of curves are different. The number of strata levels usually grows very rapidly with the number of STRATA variables, so you must be cautious when specifying the list of STRATA variables. Is equivalent to the A* B* C syntax of the TABLES statement in the FREQ procedure. The specification of STRATA variables can have any of the following forms: The initial interval is assumed to start at, and the final interval is assumed to end at. If a variable is numeric and is followed by a list, then the levels for that variable correspond to the intervals defined by the list. The corresponding strata are formed by the combination of levels. Each interval contains its lower endpoint but not its upper endpoint. More than one variable can be specified in the STRATA statement, and each numeric variable can be followed by a list. If the variable is a character variable, or if the variable is numeric and no list appears, then the strata are defined by the unique values of the strata variable. The values for variable can be formatted or unformatted. In the preceding syntax, variable is a variable whose values determine the stratum levels, and list is a list of endpoints for a numeric variable. Other options enable you to specify various k-sample tests, stratified tests, or trend tests and to make multiple-comparison adjustments for paired differences. The MISSING option can be used to allow missing values as a valid stratum level. Strata are formed according to the nonmissing values of these variables. STRATA variable > The STRATA statement identifies the variables that determine the strata levels.
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