Basic Analysis and Graphing - SAS

Chapter 2 Performing Univariate Analysis 61
Additional Examples of the Distribution Platform
Spec Limits
The Spec Limits option launches a window requesting specification limits and target, and then computes
generalizations of the standard capability indices. This is done using the fact that for the normal
distribution, 3σ is both the distance from the lower 0.135 percentile to median (or mean) and the distance
from the median (or mean) to the upper 99.865 percentile. These percentiles are estimated from the fitted
distribution, and the appropriate percentile-to-median distances are substituted for 3σ in the standard
formulas.
Related Information
• “Statistical Details for Fit Distribution Options” on page 84
Additional Examples of the Distribution Platform
This section contains additional examples using the Distribution platform.
Example of Selecting Data in Multiple Histograms
1. Open the Companies.jmp sample data table.
2. Select Analyze > Distribution.
3. Select Type and Size Co and click Y, Columns.
4. Click OK.
You want to see the type distribution of companies that are small.
5. Click on the bar next to small.
You can see that there are more small computer companies than there are pharmaceutical companies. To
broaden your selection, add medium companies.
6. Hold down the SHIFT key. In the Size Co histogram, click on the bar next to medium.
You can see the type distribution of small and medium sized companies. See Figure 2.11 at left. To
narrow down your selection, you want to see the small and medium pharmaceutical companies only.
7. Hold down the ALT key. In the Type histogram, click in the Pharmaceutical bar.
You can see how many of the small and medium companies are pharmaceutical companies. See
Figure 2.11 at right.