Note: See Saving Decision Limits Using ANOM UCHART in the SAS/QC Sample Library.
You can save the decision limits for an ANOM u chart in a SAS data set.
The following statements read the data set MSAdmits
(see Creating ANOM Charts for Rates from Group Counts) and save the decision limits displayed in Figure 4.18 in a data set named MSLimits
:
proc anom data=MSAdmits; uchart Count*ID / groupn = KMemberYrs outlimits = MSLimits nochart; run;
The GROUPN= option specifies the number of opportunity units for each group. The OUTLIMITS= option names the data set containing
the decision limits, and the NOCHART option suppresses the display of the chart. The data set MSLimits
is listed in Figure 4.19.
The data set MSLimits
contains one observation with the limits for response Count
. The variables _LDLU_
and _UDLU_
contain the lower and upper decision limits, and the variable _U_
contains the central line. The value of _LIMITN_
is the nominal number of units associated with the decision limits (which are varying in this case), the value of _LIMITK_
is the number of groups, and the value of _ALPHA_
is the significance level of the decision limits. The variables _VAR_
and _GROUP_
are bookkeeping variables that save the response and group-variable. The variable _TYPE_
is a bookkeeping variable that indicates whether the value of _U_
is an estimate or standard (known) value. Typically, the value of _TYPE_
is 'ESTIMATE.' For more information, see OUTLIMITS= Data Set.
Alternatively, you can use the OUTTABLE= option to create an output data set that saves both the decision limits and the group statistics, as illustrated by the following statements:
proc anom data=MSAdmits; uchart Count*ID / groupn = KMemberYrs outtable = MSTable nochart; run;
The a partial listing of the data set MSTable
is shown in Figure 4.20.
Figure 4.20: Data Set MSTable
Rates and Decision Limits for Medical/Surgical Admissions |
_VAR_ | ID | _ALPHA_ | _LIMITN_ | _SUBN_ | _LDLU_ | _SUBU_ | _U_ | _UDLU_ | _EXLIM_ |
---|---|---|---|---|---|---|---|---|---|
Count | 1A | 0.05 | 58.1003 | 58.1003 | 31.2135 | 32.3922 | 33.0789 | 34.9443 | |
Count | 1B | 0.05 | 12.8933 | 12.8933 | 28.2837 | 33.9710 | 33.0789 | 37.8741 | |
Count | 1C | 0.05 | 2.6633 | 2.6633 | 22.1550 | 37.5481 | 33.0789 | 44.0028 | |
Count | 1D | 0.05 | 6.8545 | 6.8545 | 26.3640 | 46.3929 | 33.0789 | 39.7938 | UPPER |
Count | 1E | 0.05 | 4.2691 | 4.2691 | 24.4964 | 40.0554 | 33.0789 | 41.6615 | |
Count | 1F | 0.05 | 0.2020 | 0.2020 | 0.0000 | 34.6535 | 33.0789 | 73.0631 | |
Count | 1G | 0.05 | 0.8626 | 0.8626 | 13.7710 | 32.4606 | 33.0789 | 52.3868 | |
Count | 1H | 0.05 | 2.3985 | 2.3985 | 21.5579 | 46.6959 | 33.0789 | 44.5999 | UPPER |
Count | 1I | 0.05 | 0.5034 | 0.5034 | 7.7757 | 49.6607 | 33.0789 | 58.3822 | |
Count | 1J | 0.05 | 1.5918 | 1.5918 | 18.8992 | 33.9249 | 33.0789 | 47.2587 |
This data set contains one observation for each group. The variables _SUBU_
and _SUBN_
contain the rate of occurrence and the number of opportunity units for each group. The variables _LDLU_
and _UDLU_
contain the lower and upper decision limits, and the variable _U_
contains the central line. The variables _VAR_
and ID
contain the response name and values of the group-variable, respectively. For more information, see OUTTABLE= Data Set.
Note: See Saving ANOM UCHART Summary Statistics and Decision Limits in the SAS/QC Sample Library.
An OUTTABLE= data set can be read later as a TABLE= data set by the ANOM procedure. For example, the following statements
read MSTable
and display a u chart (not shown here) identical to the chart in Figure 4.18:
ods graphics off; title 'Analysis of Medical/Surgical Admissions'; proc anom table=MSTable; uchart Count*id ; label _subu_ = 'Admits per 1000 Member Years'; run;
Because the ANOM procedure simply displays the information in a TABLE= data set, you can use TABLE= data sets to create specialized ANOM charts. For more information, see the section TABLE= Data Set.