Statistics Tip of the Week: Where possible, use Measurements instead of Counts in capturing data.

​In capturing data for statistical analysis, be sure to retain the information contained in measurement data, as opposed to reducing it to a count.
 
Let's say our company operates a process for producing meat patties for quarter-pound hamburgers. We want 0.25 pound burgers. Our specification limits call for all burgers to be between 0.24 and 0.26 pounds. Anything outside those limits is considered a defect.
 
We test the process quality by capturing a sample of data.  We could record the data by counting defects or by recording the actual measurement for each patty.

​When we measure 2 patties, weighing 0.23 and 0.21 pounds, if we only counted defects, we would record only the number 2 -- for 2 defects. You can see how this loses information contained in the measurements.
 
0.23 and 0.21 pounds are not equally defective. Counting them equally as 1 defect apiece makes for a less accurate assessment of process quality. 
 
So, to make the best use of the information contained in the data, we would do the analysis with measurement data, not counts.