Statistics for Six Sigma Made Easy

C.6. From Chapter 12

F Test Comparing Two Sample Sigma s, Variables Data (put the larger s on top, as the numerator) s1 = sample with the larger sigma s2 = sample with the smaller sigma The sample sizes n should be within 20% of each other. There are tables and programs that allow for greater differences, but since you control sample sizes and get more reliable results with similar sample sizes, these other tables and programs are generally not needed. Compare this Ft with the value in the simplified F table (Figure 12-3). If the Ft value exceeds the table F value, then the sigmas are significantly different.

C.6.1. Use on Problem Type

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