Question

Exam 2 Practice II 1. The Beck Depression Inventory (BDI) is a normally distributed instrument. The parameters are as follows: mean is 14 and standard deviation (a) is 3. It is widely discussed how soldiers can develop PTSD after their service. However, an Army veteran argues that although PTSD does exist, there are many soldiers that do not see any combat during their service- therefore, the Army veteran believes that when measuring all military persons, overall, veterans do not have higher levels of PTSD compared to the normal population. To test this idea, he surveyed a group of 144 veterans. They averaged 14.80. Does the data support the Army veteran's belief? Compare this sample of veterans to the normal population. i. State the null and alternative hypotheses ii. Make a decision about the null. iii. State your conclusion. iv. Relate your conclusion to the research. neeeeful and.

Answer 1

(1) The null hypothesis can be co po besis can be considerld! does, the levels of PTSD on the military persons is equal to 14. The alternate bypothesis is thai, levels of PTSD 02 the mililery persons is less than 14.. (H) je. Ho: M2 14 us His M214 (2 Based on the information provided, (x - 14.50 M214 073 12144) and assuming a 20.05%; the critical value for a left talled kst is Zez 1.64 The rejection region R. {2: 22-1.643 ,

The zo statistic is computed as: 2 X-M olon z 14.80 -14 28.01 315144 C since 3.az ze z-1.64, the null hypoth. is boz rejected. (3) Based on this study, we can o that at 95% confidence levels, the avera level of pass on the military persons is equal to 14. That is, the data donot support the army relevans belief. (4) Based on this bypothesis rest, we can say that, even when, the soldiers who don't see any combat during their service time, the PISD levels among them can be considered as a normal random variable with mean214 and standard deviation 23. ie the bisp levels among soldiers are normally distributed irrespective of their bathe field experience!

Please note : On question number 1 the null hypothesis is on an average the level of PTSD levels among soldier is 14. I missed the term on an average as it is very important. Otherwise the rest is all correct.

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