Compare Sreen

The Compare Screen is the fourth of four main charting screens in Quality Window. It is made up of three elements: the Control Chart, Histogram, and Statistics Box.

Control Chart


The Compare Screen features a Control chart that allows you to compare two separate timeframes within the same data population for one variable. Each separate data set can be sized using the tibs at the top of the chart. Limits are calculated for each data set and that portion of the chart is sized appropriately, while the limits for the overall data population remain in the background.

This view allows you to visually determine if there are different trending periods within a data population, helping you to identify possible changes in the process environment. It also will show you if changes you have made have had any impact on the process.

Dual Histogram


The Histogram chart in the Compare Screen graphically displays the distribution of each of the two data sets as it relates to variance. This first set of data is represented in dark blue, the second in light blue. The Histogram also calculates a “t test” to determine if the Average of each data set is different, as well as an “F test” to determine if the variation of each data set is different. These results are displayed below the histogram.

The results are highlighted if a significant difference was found and proven statistically. The dual capability bars on the left of the histogram help to clearly portray any differences.

Statistics Box


The Compare Screen includes a Statistics box that shows all selected statistical calculations for each data set. The two values are compared for each statistic and the difference is displayed, both as a real number and as a percentage. The number of displayed statistics can be set by the user. Additional information is available on the Statistics page.