Example of T² Chart

The sales manager of a computer software company monitors the sales figures and sales visits from the previous 26 weeks. Because the number of sales visits each week impacts the amount of sales, the manager wants to monitor these variables at the same time.

The sales manager creates a T2 chart to simultaneously monitor the mean of sales figures and sales visits over 26 weeks.

  1. Open the sample data, SoftwareSales.MTW.
  2. Choose Stat > Control Charts > Multivariate Charts > T<sup>2</sup>.
  3. In Variables, enter Sales On-Site Visits.
  4. In Subgroup sizes, enter Week.
  5. Click OK.

Interpret the results

The T2 chart shows that the process is out-of-control at point 7. The sales manager should investigate the sales data from week 7 to determine why this point is out of control.

T² Chart of Sales, On-Site Visits

Test Results for T² Chart of Sales, On-Site Visits Point Variable P-Value Greater Than UCL 7 Sales 0.0000 On-Site Visits 0.0030 * WARNING * If graph is updated with new data, the results above may no longer be correct.
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