SAS Institute. The Power to Know

SAS/QC(R) 9.2 User's Guide


BOXCHART Statement

Output Data Sets

OUTBOX= Data Set

The OUTBOX= data set saves group summary statistics, decision limits, and outlier values. The following variables can be saved:

  • the group-variable
  • the variable _VAR_, containing the analysis variable name
  • the variable _TYPE_, identifying features of box-and-whisker plots
  • the variable _VALUE_, containing values of box-and-whisker plot features
  • the variable _ID_, containing labels for outliers
  • the variable _HTML_, containing URLs associated with box-and-whisker plot features

_ID_ is included in the OUTBOX= data set only if one of the keywords SCHEMATICID or SCHEMATICIDFAR is specified with the BOXSTYLE= option. _HTML_ is present only if one or more of the HTML=, OUTHIGHHTML=, OUTLOWHTML=, or POINTSHTML= options are specified.

Each observation in an OUTBOX= data set records the value of a single feature of one group's box-and-whisker plot, such as its mean. The _TYPE_ variable identifies the feature whose value is recorded in _VALUE_. The following table lists valid _TYPE_ variable values:

Table 5.19: Valid _TYPE_ Values in an OUTBOX= Data Set
_TYPE_ Value Description
Ngroup size
ALPHAsignificance level
LIMITNnominal sample size associated with decision limits
LDLXlower decision limit for group mean
UDLXupper decision limit for group mean
RESPMEANoverall response variable mean
MINgroup minimum value
Q1group first quartile
MEDIANgroup median
MEANgroup mean
Q3group third quartile
MAXgroup maximum value
LOWlow outlier value
HIGHhigh outlier value
LOWHISKRlow whisker value, if different from MIN
HIWHISKRhigh whisker value, if different from MAX
FARLOWlow far outlier value
FARHIGHhigh far outlier value

Additionally, the following variables, if specified, are included:

  • block-variables
  • symbol-variable
  • BY variables
  • ID variables

OUTLIMITS= Data Set

The OUTLIMITS= data set saves decision limits and decision limit parameters. The following variables can be saved:

Table 5.20: OUTLIMITS= Data Set
Variable Description
_ALPHA_significance level
_DFE_degrees of freedom for mean square error
_GROUP_group-variable specified in the BOXCHART statement
_INDEX_optional identifier for the decision limits specified with the OUTINDEX= option
_LDLX_lower decision limit for group means
_LIMITK_number of groups
_LIMITN_sample size associated with the decision limits
_MEAN_weighted average of group means (\overline{\overline{x}})
_MSE_mean square error
_TYPE_type (estimate or standard value) of _MEAN_ and _MSE_
_UDLX_upper decision limit for group means
_VAR_response specified in the BOXCHART statement

Notes:

  1. In the unbalanced case, the special missing value V is assigned to the variables _LIMITN_, _LDLX_, and _UDLX_.
  2. Optional BY variables are saved in the OUTLIMITS= data set.

The OUTLIMITS= data set contains one observation for each response specified in the BOXCHART statement. For an example, see "Saving Decision Limits".

OUTSUMMARY= Data Set

The OUTSUMMARY= data set saves group summary statistics. The following variables can be saved:

  • the group-variable
  • a group minimum variable named by response suffixed with L
  • a group first-quartile variable named by response suffixed with 1
  • a group mean variable named by response suffixed with X
  • a group median variable named by response suffixed with M
  • a group third-quartile variable named by response suffixed with 3
  • a group maximum variable named by response suffixed with H
  • a group standard deviation variable named by response suffixed with S
  • a group sample size variable named by response suffixed with N

Given a response name that contains 32 characters, the procedure first shortens the name to its first 16 characters and its last 15 characters, and then it adds the suffix.

Group summary variables are created for each response specified in the BOXCHART statement. For example, consider the following statements:

  
    proc anom data=Steel; 
       xchart (Width Diameter)*Lot / outsummary=Summary; 
    run;
 

The data set Summary contains variables named Lot, WidthL, Width1, WidthX, WidthM, Width3, WidthH, WidthS, WidthN, DiameterL, Diameter1, DiameterX, DiameterM, Diameter3, DiameterH, DiameterS, and DiameterN. Additionally, the following variables, if specified, are included:

  • BY variables
  • block-variables
  • symbol-variable
  • ID variables
  • _PHASE_ (if the OUTPHASE= option is specified)

For an example of an OUTSUMMARY= data set, see "Saving Summary Statistics for Groups".

OUTTABLE= Data Set

The OUTTABLE= data set saves group summary statistics, decision limits, and related information. The following variables can be saved:

Variable Description
_ALPHA_significance level
_EXLIM_decision limit exceeded (if any)
groupvalues of the group variable
_LDLX_lower decision limit for group mean
_LIMITN_nominal sample size associated with the decision limits
_MEAN_central line
_SUBMAX_group maximum
_SUBMED_group median
_SUBMIN_group minimum
_SUBN_group sample size
_SUBQ1_group first quartile
_SUBQ3_group third quartile
_SUBX_group mean
_UDLX_upper decision limit for group mean
_VAR_response specified in the BOXCHART statement

In addition, the following variables, if specified, are included:

  • BY variables
  • block-variables
  • symbol-variable
  • ID variables
  • _PHASE_ (if the READPHASES= option is specified)

Note: The variable _EXLIM_ is a character variable of length 8. The variable _PHASE_ is a character variable of length 48. The variable _VAR_ is a character variable whose length is no greater than 32. All other variables are numeric.

For an example, see "Saving Decision Limits".