XmR Trend Control Chart in Excel

Use an XmR Trend Control Chart to evaluate stability of processes using trended data - costs (e.g., inflation).

Here is an example of an XmR Trend Control Chart created using QI Macros for Excel.

 

XmR Trend Control Chart in Excel

The Chart will calculate the fit of the data to the trend:

  • R^2 (Ryx^2) give the fit of the line to the trend. Greater than 0.80 is a good fit.
  • Ryx is the linear correlation coefficient. Compare to probability for df = n - 2.
  • Slope is the positive or negative slope of the trend
  • Sigma is the estimated standard deviation Rbar/d2
  • Probability is critical value for Ryx. If Ryx > Probability then a statistically significant correlation exists.

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To create a Xmr Trend Chart using QI Macros...
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