1. I NDUSTRIAL Q UALITY M ANAGEMENT Exponentially Weighted Moving Average Control Charts January 16, 2012

2. W EIGHTED A VERAGE C HARTS Charts from Last Week Average Range Median Standard Deviation None of these consider previous data points Weighted Average Charts Consider past history Give more importance to recent events – less to events in the distant past

3. E XPONENTIALLY W EIGHTED M OVING A VERAGE C HART Current value of response variable is a composite of current and all previous values is either set to a value between 0.2 – 0.3 or it is taken from statistical charts We will use = 0.3 for our calculations

4. S AMPLE D ATA 20 data points Historical average of this set is 50 Can use the equation on last slide Problem : Calculation gets large Can use moving average “Window”

5. F INDING C ONTROL L IMITS Calculate LCL & UCL in this manner s is the historical sample standard deviation k Set to 3, or, Use tables to make

6. EWMA A NALYSIS This is the data Calculate: EWMA (moving window) LCL UCL

7. EWMA C ONTROL C HARTS = 0.10 = 0.25