From Heather DeVries, Indiana University: I’ll make this one short and sweet…how many samples should be used in a cumulative summation study?
Heather, I’ve never used nor taught CUSUM, so I’m posting this in hopes of attracting comments. I did find a helpful reference, Westgard JO,Groth T, Aronsson T, de Verdler C. Combined Shewhart-cusum control chart for improved quality control in clinical chemistry. Clin Chem 1977; 23: 1881-1887. Looking for comments from our statistics experts.