Example of Laney U' Chart
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The staff at a hospital chain records the number of medication errors each week. Examples of errors include delivering medication at the wrong time, delivering the wrong dose, and delivering the wrong medication.

The hospital chain treats a large number of patients, an average of 7500 per week. The data exhibit a large amount of overdispersion (see Example of U Chart Diagnostic). The staff decides to use a Laney U' chart instead of a traditional U chart to monitor medication errors.

1    Open the worksheet MEDICATIONERRORS.MTW.

2    Choose Stat > Control Charts >Attributes Charts > Laney U'.

3    In Variables, enter Errors.

4    In Subgroup sizes, enter Patients. Click OK.

Graph window output

Interpreting the results

Week 23 had an unusually high number of medication errors. This data point is out of control and should be investigated.

To see the same data plotted on a traditional U chart, see Comparing traditional U charts and Laney U' charts.