1. Control Charts Other Variable Control Charts Chapter Seven

2. Control Charts Other chart options  What happens when there is an insufficient number of sample measurements to create x-bar and r charts?  What happens when only one sample is taken?  What other charting methods are available?

3. Control Charts Available chart options  Individual and Moving-Range  Moving-Average and Moving-Range  All Individual Values  Median and Range charts  Run charts  Variable sub-group size  Pre-control charts

4. Control Charts Individuals and Moving- Range  Used when measurements are single values or when the number of products produced is too small to form traditional charts.  Moving ranges are calculated by measuring the value-to-value differences.  Interpretation is the same - check trends, runs, patterns, limits

5. Control Charts Moving-average and Moving-range  Plot moving-average replace oldest value with newest value sample size n = number of selected values  Moving-averages smooth out short-term variation  Lags occur, charts are less sensitive to change

6. Control Charts All individual values  Cluttered looking  Useful when examining individual variation

7. Control Charts Median and Range charts  Median of the data is calculated and charted  Ease of calculation is a trade-off with some loss of sensitivity.  Constructed and interpreted like X-bar/R charts

8. Control Charts Run charts  Used to monitor process changes associated with a particular characteristic over time.  Either variables or attribute data.  X-axis shows time.  Y-axis shows attribute/variable value.

9. Control Charts Charts for variable sub- group size  Sub-group size coefficients must be recalculated  Each subgroup with a different sample size will have its own control limits plotted.  Con: lots of calculations!

10. Control Charts Pre-control charts  Study and compare product produced with tolerance limits.