Saturday 21 June 2014

Statistical process control charts!

The Matrix Gemini Laboratory Information System (LIMS) from Autoscribe can be readily configured to display Statistical Process Control (SPC) charts using its unique One Time Configuration tools. These charts and their associated statistics can be placed on to any Matrix screen using the screen editor. They can be used to monitor the processes involved in manufacturing and product development to reveal trends, identify areas for potential improvement and detect serious problems. Matrix Gemini allows Trend, Histograms, R-Charts and X-Charts to be generated.

Trend charts include user-specified upper and lower limits. If these levels are not set, the upper and lower control limits are automatically set using the 95% confidence rule. Trend charts are particularly useful as they can reveal if a process is moving towards one of the limits, allowing remedial action to be taken in good time. Trending can be based on date, name or index. Histogram charts display the frequency distribution of sample data. An overlay can also be displayed showing the expected random distribution based on the mean and variance of the data.

The (individual) X-Chart displays the numerical values of the supplied data, while the moving R-Chart displays a moving range corresponding to each of the individual numeric values of the (individual) X-Chart. For each chart type, upper and lower control limits are calculated and divided into six zones. Any unnatural variation within the numeric values is determined using the ‘Nelson Rules’ approach and can be automatically highlighted on the control chart by circling them in red.

A number of important statistics, many of them common to all of the charts, can be displayed. Statistical values available include: specification limits, control limits, average value, average range, standard deviation, variance and capability indices (Cp and Cpk).

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