PROC HPSUMMARY Statement :: Base SAS(R) 9.4 Procedures Guide: High-Performance Procedures, Second Edition

PROC HPSUMMARY Statement

Subsections:

Optional Arguments

PROC HPSUMMARY <options> <statistic-keywords> ;

The PROC HPSUMMARY statement invokes the procedure. The HPSUMMARY procedure computes descriptive statistics for variables across all observations or within groups of observations.

Table 10.1 summarizes the available options in the PROC HPSUMMARY statement by function. The options are then described fully in alphabetical order in the section Optional Arguments. For information about the statistic-keywords, see the section Statistic Keywords.

Table 10.1: PROC HPSUMMARY Statement Options

Option	Description
Basic Options
DATA=	Specifies the input data set
PCTLDEF=	Specifies the mathematical definition used to compute quantiles
Option Related to Classification Level
MISSING	Uses missing values as valid values to create combinations of classification variables
Options Related to the Output Data Set
ALLTYPES	Computes statistics for all combinations of classification variables (not just the $n$ -way)
CHARTYPE	Specifies that the _TYPE_ variable contain character values
Options Related to Statistical Analysis
ALPHA=	Specifies the confidence level for the confidence limits
EXCLNPWGT	Excludes observations with nonpositive weights from the analysis
QMARKERS=	Specifies the sample size to use for the P2 quantile estimation method
QMETHOD=	Specifies the quantile estimation method
QNTLDEF=	Specifies the mathematical definition used to compute quantiles
statistic-keywords	Selects the statistics
VARDEF=	Specifies the variance divisor

Optional Arguments

You can specify the following options in the PROC HPSUMMARY statement:

ALLTYPES ALLWAYS

requests that PROC HPSUMMARY compute descriptive statistics for all combinations of classification variables. By default, PROC HPSUMMARY generates only the $n$ -way. For more information, see the section How PROC HPSUMMARY Groups Data.

ALPHA= value

specifies the confidence level to compute the confidence limits for the mean. The percentage for the confidence limits is 100(1–value). For example, ALPHA=0.05 results in a 95% confidence limit. You can specify any value between 0 and 1. The default is 0.05. To compute confidence limits, specify the statistic-keyword CLM, LCLM, or UCLM. See the section Confidence Limits.

CHARTYPE

specifies that the _TYPE_ variable in the output data set is a character representation of the binary value of _TYPE_. The length of the variable equals the number of classification variables. When you specify more than 32 classification variables, _TYPE_ automatically becomes a character variable. See the section Output Data Set.

DATA= SAS-data-set

names the SAS data set to be used as the input data set. The default is the most recently created data set.

EXCLNPWGT EXCLNPWGTS

excludes observations with nonpositive weight values (0 or negative) from the analysis. By default, PROC HPSUMMARY treats observations with negative weights like observations with zero weights and counts them in the total number of observations. See the WEIGHT= option and the section WEIGHT Statement.

MISSING

considers missing values as valid values to create the combinations of classification variables. Special missing values that represent numeric values—the letters A through Z and the underscore (_) character—are each considered as a separate value. If you omit MISSING, then PROC HPSUMMARY excludes the observations with a missing classification variable value from the analysis. See SAS Language Reference: Concepts for a discussion of missing values that have special meanings.

PCTLDEF=1 | 2 | 3 | 4 | 5

is an alias for the QNTLDEF= option.

QMARKERS= number

specifies the default number of markers to use for the $P^2$ quantile estimation method. The number of markers controls the size of fixed memory space.

The value of number must be an odd integer greater than 3. The default value depends on which quantiles you request. For the median (P50), number is 7. For the quantiles (P25 and P50), number is 25. For the quantiles P1, P5, P10, P75 P90, P95, or P99, number is 105. If you request several quantiles, then PROC HPSUMMARY uses the largest value of number.

You can improve the accuracy of the estimate by increasing the number of markers above the default settings; you can conserve memory and computing time by reducing the number of markers. See the section Quantiles.

QMETHOD=OS | P2

specifies the method that PROC HPSUMMARY uses to process the input data when it computes quantiles. If the number of observations is less than or equal to the QMARKERS= value and QNTLDEF=5, then both methods produce the same results. The QMETHOD= option can take either of the following values:

OS

specifies that PROC HPSUMMARY use order statistics.

Note: This technique can be very memory-intensive.

P2

specifies that PROC HPSUMMARY use the $P^2$ method to approximate the quantile. When QMETHOD=P2, PROC HPSUMMARY does not compute MODE or weighted quantiles. In addition, reliable estimations of some quantiles (P1, P5, P95, P99) might not be possible for some data sets.

The default is OS. See the section Quantiles for more information.

QNTLDEF=1 | 2 | 3 | 4 | 5 PCTLDEF=1 | 2 | 3 | 4 | 5

specifies the mathematical definition that PROC HPSUMMARY uses to calculate quantiles when QMETHOD=OS. The default is 5. To use QMETHOD=P2, you must use QNTLDEF=5. See the section Quantile and Related Statistics.

VARDEF= divisor

specifies the divisor to use in the calculation of the variance and standard deviation. Table 10.2 shows the possible values for divisor and their associated formulas.

Table 10.2: Values for VARDEF= Option

divisor	Description	Formula for Divisor
DF	Degrees of freedom	$n - 1$
N	Number of observations	$n$
WDF	Sum of weights minus one	$\left(\sum _ i w_ i\right) - 1$
WEIGHT \| WGT	Sum of weights	$\sum _ i w_ i$

The procedure computes the variance as CSS divided by divisor, where the corrected sum of squares CSS is defined by the following formula:

$\mbox{CSS} = \sum \left( x_ i - \bar{x} \right)^2$

When you weight the analysis variables, the formula for CSS is

$\mbox{CSS} = \sum w_ i \left( x_ i - \bar{x}_ w \right)^2$

where $\bar{x}_ w$ is the weighted mean.

The default is DF. To compute the standard error of the mean, confidence limits for the mean, or the Student’s $t$ -test, you must use this default value.

When you use the WEIGHT statement and VARDEF=DF, the variance is an estimate of $\sigma ^2$ , where the variance of the $i$ th observation is $\mbox{var} (x_ i) = \sigma ^2 / w_ i$ and $w_ i$ is the weight for the $i$ th observation. This method yields an estimate of the variance of an observation with unit weight. When you use the WEIGHT statement and VARDEF=WGT, the computed variance is asymptotically (for large $n$ ) an estimate of $\sigma ^2 / \bar{w}$ , where $\bar{w}$ is the average weight. This method yields an asymptotic estimate of the variance of an observation with average weight. See the section Keywords and Formulas.

The HPSUMMARY Procedure

PROC HPSUMMARY Statement

Optional Arguments