BOXCHART Statement: ANOM Procedure

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 links 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 the HTML= or HTML2= option is 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_. Table 4.3 lists the valid _TYPE_ variable values:

Table 4.3: Valid _TYPE_ Values in an OUTBOX= Data Set

_TYPE_ Value

Description

N

Group size

ALPHA

Significance level

LIMITN

Nominal sample size associated with decision limits

LDLX

Lower decision limit for group mean

UDLX

Upper decision limit for group mean

RESPMEAN

Overall response variable mean

MIN

Group minimum value

Q1

Group first quartile

MEDIAN

Group median

MEAN

Group mean

Q3

Group third quartile

MAX

Group maximum value

LOW

Low outlier value

HIGH

High outlier value

LOWHISKR

Low whisker value, if different from MIN

HIWHISKR

High whisker value, if different from MAX

FARLOW

Low far outlier value

FARHIGH

High 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 4.4: 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:

Table 4.5: continued

Variable

Description

_ALPHA_

Significance level

_EXLIM_

Decision limit exceeded (if any)

Group

Values 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.