SPC Study Type

The SPC Study Type defines which statistics are calculated for each subgroup. This table lists the various SPC study types:

Study Type	Description
Process-IXMR	The Individual X, Moving Range (IXMR) study type tracks the range within each subgroup, calculated as the difference between the highest and lowest value. The X chart displays each individual measurement, while the R chart displays the moving (or rolling) range.
Process-IXMRR	This study type is similar to the Process-IXMR, however, includes an additional chart for the range within each piece.
Process-IXMS	The Individual X, Moving Standard Deviation (IXMS) study type tracks the standard deviation within each subgroup. The X chart displays each individual measurement, while the S chart displays the rolling (or moving) standard deviation.
Process-IXPpPpk	This is a specialised chart where the X chart displays individual X values, while charts 2 and 3 displays the rolling calculations of Pp and Ppk. Only a few companies use this chart to track how capability indices grow over time.
Process-MPpPpk	This study type is a specialised chart designed for studies with a sample size of one, where chart 1 displays the rolling calculation of Pp and chart 2 displays the rolling calculation of Ppk. Only a few companies use this chart to observe capability index trends over time.
Process-MXMR	The Moving X, Moving Range (MXMR) study type focuses on monitoring the range within each subgroup, calculated as the difference between the maximum and minimum values. In this study, the X chart displays the moving average of measurement values, while the R chart displays the moving (rolling) range.
Process-MXMRR	This study is similar to the Process-MXMR analysis, however, includes an additional chart for the range within each piece.
Process-MXMS	The Moving X and Moving Range (MXMS) study type tracks the standard deviation within each subgroup. In this method, the X chart displays the moving average of measurement values, while the S chart displays the rolling standard deviation.
Process-MXPpPpk	This study type is a specialist chart that displays the moving average of X values on the X chart, alongside the rolling calculations of Pp and Ppk on charts 2 and 3. Only a few companies use this chart to observe capability index trends over time.
Process-PpPpk	This study type is a specialised chart displays the ongoing calculation of Pp on chart 1 and Ppk on chart 2. Used by a small number of companies to assess capability trends.
Process-XbarPpPpk	This study type chart is specifically designed for studies with a sample size greater than one, displaying the continuous calculation of Pp on chart 1 and Ppk on chart 2. Only a few companies use this chart to observe capability index trends over time.
Process-XbarR	This study type is a standard process capability chart features an X chart that displays the average value of each subgroup (usually measured simultaneously), alongside an R chart that displays the range within those subgroups.
Process-XbarRR	This study type resembles the Process-XbarR method; however, this method includes an additional range chart that displays the variation within each piece.
Process-XbarR	This study type is a standard process capability chart displays an X chart displaying the average of each subgroup—usually measured concurrently. This is alongside an S chart, which indicates the standard deviation within those subgroups.
Run	Typically used in attribute charts to display the total number of defects counted.

Each study type includes an X chart, which displays individual measurements or the average of multiple values. The X chart is an R chart, which displays the range, or an s chart, which displays the standard deviation. In some cases, an additional chart is also provided to display the variation within individual pieces.