Quality Control
Charts: S Chart
Suppose that you are trying to monitor the amount of moisture in a fabric. (This data is listed in the STA 3032 notes.) Five measurements were taken at a time.
Enter Data where
each row is a sample:
To
do this entire sample 1, in row 1. Enter sample 2 in row 2.
- If
you want to do a s Chart with s as an approximation of sigma, go to Stat, Control Charts, Variables charts
for subgroups, X-bar-s. The
following image will appear.
- Select “Observations for a subgroup are in one row of
columns”.
- Enter the columns, which contain your data.
- Click on X-bar-S options and click on Estimate. The
figure below will appear.
- Select Sbar.
- Click o.k. twice. The following graph will appear. The
top chart is an X-bar chart that uses s to estimate sigma. The second
graph is an s chart.
