PROC CAPABILITY: Output Data Sets

Output Data Sets

You can create two output data sets with the HISTOGRAM statement: the OUTFIT= data set and the OUTHISTOGRAM= data set. These data sets are described in the following sections.

OUTFIT= Data Set

The OUTFIT= data set contains the parameters of fitted density curves, information about chi-square and EDF goodness-of-fit tests, specification limit information, and capability indices based on the fitted distribution. Since you can specify multiple HISTOGRAM statements with the CAPABILITY procedure, you can create several OUTFIT= data sets. For each variable plotted with the HISTOGRAM statement, the OUTFIT= data set contains one observation for each fitted distribution requested in the HISTOGRAM statement. If you use a BY statement, the OUTFIT= data set contains several observations for each BY group (one observation for each variable and fitted density combination). ID variables are not saved in the OUTFIT= data set.

The OUTFIT= data set contains the variables listed in Table 5.24. By default, an OUTFIT= data set contains _MIDPT1_ and _MIDPTN_ variables, whose values identify histogram intervals by their midpoints. When the ENDPOINTS= or NENDPOINTS option is specified, intervals are identified by endpoint values instead. If the RTINCLUDE option is specified, the variables _MAXPT1_ and _MAXPTN_ contain upper endpoint values. Otherwise, the variables _MINPT1_ and _MINPTN_ contain lower endpoint values.

Table 5.24 Variables in the OUTFIT= Data Set
Variable	Description
_ADASQ_	Anderson-Darling EDF goodness-of-fit statistic
_ADP_	p-value for Anderson-Darling EDF goodness-of-fit test
_CHISQ_	chi-square goodness-of-fit statistic
_CP_	generalized capability index $\text{[math]}$ based on the fitted curve
_CPK_	generalized capability index $\text{[math]}$ based on the fitted curve
_CPL_	generalized capability index CPL based on the fitted curve
_CPM_	generalized capability index $\text{[math]}$ based on the fitted curve
_CPU_	generalized capability index CPU based on the fitted curve
_CURVE_	name of fitted distribution (abbreviated to 8 characters)
_CVMWSQ_	Cramer-von Mises EDF goodness-of-fit statistic
_CVMP_	p-value for Cramer-von Mises EDF goodness-of-fit test
_DF_	degrees of freedom for chi-square goodness-of-fit test
_ESTGTR_	estimated percent of population greater than upper specification limit
_ESTLSS_	estimated percent of population less than lower specification limit
_ESTSTD_	estimated standard deviation
_EXPECT_	estimated mean
_K_	generalized capability index $\text{[math]}$ based on the fitted curve
_KSD_	Kolmogorov-Smirnov EDF goodness-of-fit statistic
_KSP_	p-value for Kolmogorov-Smirnov EDF goodness-of-fit test
_LOCATN_	location parameter for fitted distribution. For the Gumbel, inverse Gaussian, and normal distributions, this is either the value of $\text{[math]}$ specified with the MU= option or the value estimated by the procedure. For all other distributions, this is either the value specified or estimated according to the THETA= option, or zero.
_LSL_	lower specification limit
_MAXPT1_	upper endpoint of first interval used to calculate the value of the chi-square statistic.
_MAXPTN_	upper endpoint of last interval used to calculate the value of the chi-square statistic.
_MIDPT1_	midpoint of first interval used to calculate the value of the chi-square statistic. This is the leftmost interval that contains at least one value of the variable.
_MIDPTN_	midpoint of last interval used to calculate the value of the chi-square statistic. This is the rightmost interval that contains at least one value of the variable.
_MINPT1_	lower endpoint of first interval used to calculate the value of the chi-square statistic.
_MINPTN_	lower endpoint of last interval used to calculate the value of the chi-square statistic.
_OBSGTR_	observed percent of data greater than upper specification limit
_OBSLSS_	observed percent of data less than the lower specification limit
_PCHISQ_	p-value for chi-square goodness-of-fit test
_SCALE_	value of scale parameter for fitted distribution. For the lognormal distribution, this is the value of $\text{[math]}$ specified or estimated according to the ZETA= option. For all other distributions, this is the value specified or estimated according to the SIGMA= option.
_SHAPE1_	value of shape parameter for fitted distribution. For the beta, gamma, generalized Pareto, and power function distributions, this is the value of $\text{[math]}$ , either specified with the ALPHA= option or estimated by the procedure. For the lognormal distribution, this is the value of $\text{[math]}$ , either specified with the SIGMA= option or estimated by the procedure. For the Weibull distribution, this is the value of $\text{[math]}$ , either specified with the C= option or estimated by the procedure. For the Johnson $\text{[math]}$ and $\text{[math]}$ distributions, this is the value of $\text{[math]}$ , either specified with the DELTA= option or estimated by the procedure. For distributions without a shape parameter (Gumbel, normal, exponential, and Rayleigh distributions), _SHAPE1_ is set to missing.
_SHAPE2_	value of shape parameter for fitted distribution. For the beta distribution, this is the value of $\text{[math]}$ , either specified with the BETA= option or estimated by the procedure. For the Johnson $\text{[math]}$ and $\text{[math]}$ distributions, this is the value of $\text{[math]}$ , either specified with the GAMMA= option or estimated by the procedure. For all other distributions, _SHAPE2_ is set to missing.
_TARGET_	target value
_USL_	upper specification limit
_VAR_	variable name
_WIDTH_	width of histogram interval

OUTHISTOGRAM= Data Set

The OUTHISTOGRAM= data set contains information about histogram intervals. Since you can specify multiple HISTOGRAM statements with the CAPABILITY procedure, you can create multiple OUTHISTOGRAM= data sets.

The data set contains a group of observations for each variable plotted with the HISTOGRAM statement. The group contains an observation for each interval of the histogram, beginning with the leftmost interval that contains a value of the variable and ending with the rightmost interval that contains a value of the variable. These intervals will not necessarily coincide with the intervals displayed in the histogram since the histogram may be padded with empty intervals at either end. If you superimpose one or more fitted curves on the histogram, the OUTHISTOGRAM= data set contains multiple groups of observations for each variable (one group for each curve). If you use a BY statement, the OUTHISTOGRAM= data set contains groups of observations for each BY group. ID variables are not saved in the OUTHISTOGRAM= data set.

The OUTHISTOGRAM= data set contains the variables listed in Table 5.25. By default, an OUTHISTOGRAM= data set contains the _MIDPT_ variable, whose values identify histogram intervals by their midpoints. When the ENDPOINTS= or NENDPOINTS option is specified, intervals are identified by endpoint values instead. If the RTINCLUDE option is specified, the _MAXPT_ variable contains an interval’s upper endpoint value. Otherwise, the _MINPT_ variable contains the interval’s lower endpoint value.

Table 5.25 Variables in the OUTHISTOGRAM= Data Set
Variable	Description
_COUNT_	number of variable values in histogram interval
_CURVE_	name of fitted distribution (if requested in HISTOGRAM statement)
_EXPPCT_	estimated percent of population in histogram interval determined from optional fitted distribution
_MAXPT_	upper endpoint of histogram interval
_MIDPT_	midpoint of histogram interval
_MINPT_	lower endpoint of histogram interval
_OBSPCT_	percent of variable values in histogram interval
_VAR_	variable name

OUTKERNEL= Output Data Set

An OUTKERNEL= data set contains information about kernel density estimates requested with the KERNEL option. Because you can specify multiple HISTOGRAM statements with the CAPABILITY procedure, you can create multiple OUTKERNEL= data sets.

An OUTKERNEL= data set contains a group of observations for each kernel density estimate requested with the HISTOGRAM statement. These observations span a range of analysis variable values recorded in the _VALUE_ variable. The procedure determines the increment between values, and therefore the number of observations in the group. The variable _DENSITY_ contains the kernel density calculated for the corresponding analysis variable value.

When a density curve is overlaid on a histogram, the curve is scaled so that the area under the curve equals the total area of the histogram bars. The scaled density values are saved in the variable _COUNT_, _PERCENT_, or _PROPORTION_, depending on the histogram’s vertical axis scale, determined by the VSCALE= option. Only one of these variables appears in a given OUTKERNEL= data set.

Table 5.26 lists the variables in an OUTKERNEL= data set.

Table 5.26 Variables in the OUTKERNEL= Data Set
Variable	Description
_C_	standardized bandwidth parameter
_COUNT_	kernel density scaled for VSCALE=COUNT
_DENSITY_	kernel density
_PERCENT_	kernel density scaled for VSCALE=PERCENT (default)
_PROPORTION_	kernel density scaled for VSCALE=PROPORTION
_TYPE_	kernel function
_VALUE_	variable value at which kernel function is calculated
_VAR_	variable name

HISTOGRAM Statement: CAPABILITY Procedure

Output Data Sets

OUTFIT= Data Set

OUTHISTOGRAM= Data Set

OUTKERNEL= Output Data Set