Test Sensitivity by Mohamad Hisham Hamdan MBB

Purpose

The test sensitivity is how much difference needs to be detected in a hypothesis test of the mean in order for an effect to be practically significant when the amount of risk for both ? (alpha) and ? (beta) has been fixed. This difference is referred to as “delta sigma” and is designated as  d/s . Test sensitivity plays big role especially during the decision for sample size selection during analyze and improve phase.

bt-17-test-sensitivity

Anatomy


Reference:      The Vision of Six Sigma: Tools and Methods for Breakthrough by M. J. Harry Ch. 13, P. 11-14, Ch. 14, P. 23

 

Terminology

A.   d (delta) - The difference in means that we want to be able to detect with the test.

B.   Control Distribution - Distribution associated with the null (H0) hypothesis.

C.   (1-?? - Confidence level: confidence that an observed outcome in the sample is “real”.

D.   Contrast Distribution - Distribution associated with the alternate (Ha) hypothesis.

E.     (1-?? - Power of the test: chance of detecting a specified change in the population with the sample if the difference is actually there to detect.

F.    d/s -The difference in means that we want to be able to detect with the test expressed in standard deviation units. It is a direct measure of test sensitivity; i.e., the difference between two means expressed in standard deviation units. By fixing this value in advance of a test, we are able to align practical significance with statistical significance.


Information About Article

Date:
10.12.09
Category:
Advanced Practitioners Track