Wednesday, May 9, 2012

How Minitab draws the line and determines significant effects on the normal plot of the effects

In the last knowledge sharing session, I share about 2k factorial DOE with Minitab. Somebody ask how actually Minitab define the red line in the Pareto Chart of Effect, and what is Lenth's PSE

Answer given to the audiance during the knowledge session was : sorry, I don't know.
Anyway, I try to find out the asnwer yesterday and here the answer I get.

Reference document

I try to work out the number with the example I shared, fortunately, I manage to workout the answer manually.

Just follow the step below, I believe you guy can get the answer as well

Step 1 : Stat > DOE > Analyse Factorial Design
Check Storage & Effect as shown in the picture below

Copy the value of EFFE1 and paste it into Excel for manual calculation
Table as shown in the picture below. You should able to get Lenth's PSE of 11.4375

In Minitab, the Red Line of Pareto chart is named as Margin Error (ME).
ME = t x Lenth's PSE

Where t can be find from t distribution.
Cal > Probability Distribution > t
Refer to Ref Document above.

Finally, I got the answer.


vixullase said...

you are using which version of Minitab. I am not able to find the effect box in the tab


Vicky Varghese

I Talk - You Do said...

Hi Vicky
That is Version 14