March 2002

Vol. 4, No. 3

Quality Quiz

May Aculpa, quality manager for No Fault Candles, Inc., has noticed that the quality of wax produced in No Fault's factory diminishes in warm weather, even though the plant is air conditioned and the temperature inside remains relatively constant. Her boss, Gil T. Party, tells her to undertake some statistical analysis to establish the pattern that she has observed.

May collects data relating to the number of defective candles produced each day, and at the same time keeps track of daily high temperatures recorded by the weather bureau. Without complex analysis, she can see even from the raw data that the higher the temperature, the greater number of defective candles produced. Nonetheless, in order to satisfy Gil's requirements, she decides to do an individual moving range chart with the data she has collected.

After she has produced the charts and examined them for patterns, another associate, Cyn N. Kruption, insists that she has used the wrong statistical method, although Cyn herself cannot advise what approach would be better. Is May Aculpa correct in using an individual moving range chart, or is there a better way to analyze this data?

a) May should abandon her chart and take an Alka Seltzer. It's too hot outside to think.

b) An individual moving range chart provides insights about the data that no other method can give.

c) Cyn N. Kruption is on the right track, but the wrong train. She should advise May to use a scatter diagram to get the best analysis of the data.

d) Since she already knows that there is a relationship between defects and temperature, she should select the chart that will be most dramatic, so she can impress Gil T. Party with her statistical prowess.

Click on the correct answer, and link to the solution.


Copyright 2002 PQ Systems.

Please direct questions or problems regarding this web site to the Webmaster.