Confidence regions for the ratio of percentiles

Motivated by applications in the lumber industry, we derive confidence regions for the ratio of percentiles from two different populations. Generalizing work on inferences concerning the ratio of two means, we develop an exact confidence procedure when the two populations are normal and have the same variance. Other cases for normal populations are treated by large sample methods. General populations are also treated in a large sample context. The different large sample procedures are compared with a small simulation study. An example, using strength of lumber data, is also given.Non-central t distribution non-parametric estimation Strength of lumber Large sample comparisons