The Capability Analysis (Binomial) generates a process capability report containing various capability indices. It is used when the data is from a binomial distribution.
1. Choose ProcessMA > Quality Tools > Capability Analysis > Capability Analysis (Binomial).
2. In Defectives, select the column containing the data.
· For constant sample size:
- Check Constant size.
- In Sample size(s), enter the sample size.
· For non-constant sample size:
- Uncheck Constant size.
- In Sample size(s), select the column containing the sample sizes.
Optional
3. In Historical p, enter the historical proportion of defectives.
4. In Target % defective, enter the percent defective target.
Note To select a column of data into a textbox, double-click on any of the column names shown in the list on the left of the dialog box while in the textbox.
Defectives: Integer.
Sample size(s): Integer.
Historical p: Numeric; Between 0 and 1.
Target % defective: Numeric; between 0 and 100.
You are working in a software company and you want to assess the responsiveness of the customer support service. You recorded the number of enquiries received and the number of enquiries unresolved after 2 days, for the last 30 days.
1. Open worksheet ProcessMA > Tools > Data Files > Control.xls.
2. Choose ProcessMA > Quality Tools > Capability Analysis > Capability Analysis (Binomial).
3. In Defectives, select N – Unresolved.
4. In Sample size(s), select O – Enquiries.
5. Click OK.
Interpretation
The P Chart shows that the process is in control. The Cumulative % Defective shows the overall defectives settles at 12.4%. The rate of defectives seems to increase with sample size. The process Z is only 1.15, which means that the process needs much improvement.