Question

An observational study of Alzheimer's disease (AD) obtained data from 15 AD patients exhibiting moderate dementia and selected a group of 7 control individuals without AD. AD is a progressive neurodegenerative disease of the elderly and advancing age is known to be a primary risk factor in AD diagnosis. Therefore, it was crucial for the study's credibility to examine whether the ages in the AD group might be significantly different than in the control group. The ages of the subjects in years are summarized in the Minitab Output below.

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Descriptive Statistics: Alzheimers, Control

Variable	N	N*	Mean	SE Mean	StDev	Minimum	Q1	Median	Q3	Maximum
Alzheimers	15	0	78.52	1.77	6.87	77.00	79.25	87.00	92.25	93.00
Control	7	0	67.43	4.87	12.88	54.00	56.00	65.00	82.00	89.00

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We want to test if the average age in the Alzheimer's group is significantly different than the control group.  

(a)	What is the null hypothesis?

(b)	Find the value of the test statistic.

(c)	Find the 5% critical value.

(d)	What is the conclusion of the hypothesis test?

Answer 1

a)

a)

What is the null hypothesis Ho μ1 =μ2

b)

test stat t =(x1-x2-Δo)/Se=

2.1404

c)

for 0.05 level ,two tail test &7 df, critical t=

2.365

d)

fail ro reject ho since absolute value in b is not greater than part c)