Managing SPC Sessions
Related Topics Overview
The term statistical process control (SPC) refers to the ability to monitor a process (that is, a production line or plant) to ensure that the process is always within statistical control, that is, the process is continuing to perform in the manner it was intended, based on statistically measured parameters.
Typically a laboratory is involved in analysing samples from a process or plant, where both the process and the analytical procedure needs to be constantly checked for movements away from the expected outcome. To monitor this process, the laboratory receives samples for analysis, and the results are checked against pre-determined limits. For example, sulphur in a grade of steel must always be between 0.050 and 0.070 percent. If the result exceeds these limits, then this indicates that the process should possibly be altered or adjusted to bring the grade back into specification.
CCLAS uses the term "product" to refer to a material or sample type that can be defined in terms of an expected range of results for a particular analytical technique.
As well as monitoring the process, the laboratory needs to monitor its ability to generate a correct result. This may mean checking the calibration or drift of analytical instruments by regularly analysing what CCLAS refers to as "standards". The main difference between a Standard and a Product is that a product has upper and lower limits, while a Standard has a statistically expected result, with a variation that should follow a normal distribution around the expected result.
The way the SPC application functions is to establish some product and/or standard samples with regard to their limits and parameters. As each sample (or type) is analysed by the On-line or Data Entry applications, the SPC charts that contain the various statistical data based on the analytical results, are updated with that latest result.
This process is pertinent to LIMS and laboratory managers who configure the LIMS and quality control (QC) performance analysis sessions, in particular.
Process
SPC sessions are managed using the SPC application.
Pre-configured plots for a SPC session are displayed during the analytical process to track the performance of BLK and STD quality control types and products. Keep a plot window active to view QC results as they are updated in CCLAS.
Display one or more plots for a SPC session
The charts in the SPC application are drawn using Olectra Chart™. The chart can be interacted with as it is running to examine data more closely, or to visually isolate a part of the chart. The following interactions affect the chart displayed inside the chart area. Other chart elements (for example, header) are not affected).
The plot itself can be interacted with to change the scale, move the chart, zoom an area on the chart, zoom the chart axis, rotate the chart, or return to the original presentation. A graphics zoom enlarges the selected area of a chart, while not necessarily showing the axes. An axis zoom changes the minimum and maximum data values to those selected, and redraws only that data with axes.
Where the LIMS is configured to show the toolbar on SPC plots, various flows are available from each plot to view, report or print plot data, view or change the chart's properties, or change the plot type. Where no toolbar is shown, most actions are accessible via the main menu.
