Data Analysis with Microsoft Excel: Updated for Office 2007

516 Statistical Methods

The Pareto chart displayed in Figure 12-20 shows that a majority of

the rejects come from a few heads. Filler head 18 accounts for 87 of the

defects, and the fi rst three heads in the chart (18, 14, and 23) account for

almost 40% of all of the defects. There might be something physically

wrong with the heads that made them more liable to clogging up with

powder. If rejects were being produced randomly from the fi ller heads,

you would expect that each fi ller head would produce 1 / 24 , or about 4%,

of the total rejects. Using the information from the Pareto chart shown in

Figure 12-18, you might want to repair or replace those three heads in or-

der to reduce clogging.

You can close the Powder Pareto Chart workbook now, saving your

changes.

Figure 12-20

Pareto chart

for the

power data

plot of cumulative

percentage

more of the defects come

from filler head 18 than

from any other filler head