Post-traumatic stress of POWs. Psychological Assessment

(Mar. 1995) published the results of a study of World War II aviators captured by German forces after having been shot down. Having located a total of 239 World War II aviator POW survivors, the researchers asked each veteran to participate in the study; 33 responded to the letter of invitation.

Each of the 33 POW survivors was administered the Minnesota Multiphasic Personality Inventory, one component of which measures level of post-traumatic stress disorder (PTSD). [Note: The higher the score, the higher is the level of PTSD.] The aviators produced a mean PTSD score of x = 9.00 and a standard deviation of s = 9.32.

Conduct a test to determine if the true mean PTSD score for all World War II aviator POWS is less than 16. [Note:

The value 16 represents the mean PTSD score established for Vietnam POWS.] Use a = .10.