AAOM Handbook

INTERNAL

AI.01 Produce Control Charts Context

A Key Performance Indicator or Control Measure is produced for the purpose of helping us make the decisions necessary to control or improve a process. An appropriate intervention in a process, taken at the right time, can ensure that the performance is maintained or improved. Every un-necessary intervention in a process tends to increase the variation in, and losses produced by, the process. It is therefore essential that only the necessary and appropriate interventions be made. Making the right decision on the need for intervention is dependent on having the right data, and on making the correct interpretation of the data. The Set Performance Targets process established what the Key Performance measures are for each process and the TAs related to Measure Output, Work Management and Social performance defined how these are measured. Control measures are defined through the tools used during the Analyse and Improve process. Statistical analysis tools help us to take the guesswork out of interpretation of the data, and to decide the appropriate and in-appropriate times for intervention in a process. The most common tools we will use for guiding the decision to intervene in a process are Control charts and Capability Histograms. Purpose To provide the information necessary for making a decision that intervention in a process is required. Quantity One set of appropriate Control Charts for each of the measured variables. Quality Each chart shall be constructed;  To a common format; o display the data, Upper Control Limit, Lower Control Limit and Mean on the Control Chart, o display the data, Upper Specification Limit, Lower Specification Limit, Mean and total number of data points on the Capability Histogram.  Using standardised out of control tests – as a guide, start by using the following basic tests; o a point outside of a Control Limit, o seven points above or below the Mean, o seven points ascending or descending o a recurring pattern or tendency  Using standardised rules for setting and changing control limits, See Appendix 1 for detailed Guidelines.