Statistics for Six Sigma Made Easy

12.5. WHAT WE HAVE LEARNED IN CHAPTER 12

1. Valid sampling and analysis of variables data are needed for the Define, Measurement, Analysis, and Control steps in the DMAIC process.

2. Variables data are usually in decimal form, with no discrete "steps."

3. 11 is the rule-of-thumb minimum sample size on variables data.

4. When possible, use the formulas to determine minimum sample size.

5. We seldom have complete data on a population, but use samples to estimate its composition.

6. The greater the sample size, the better the estimate on the population.

7. Sample size is usually a compromise between cost and desire for accuracy.

8. We normally work to a 95% confidence test level.

9. Assume two-tailed (high and low) problems unless specifically indicated as one-tailed.

10. We normally ...