Problem 2: Use an alpha level of 0.05 for all relevant questions. Problem 2 shou
ID: 3367165 • Letter: P
Question
Problem 2:
Use an alpha level of 0.05 for all relevant questions.
Problem 2 should be solved by hand and tables. All calculations can be done using excel or any other software.
Deep brain stimulation (DBS) has been used to treat several brain disorders such as depression. Suppose a research team is interested in investigating the effectiveness of using DBS to reduce depression by stimulating a new area in the brain; the ventral capsule/ventral striatum. In this particular study, the researchers decided to use each participant as their own control. Assume the following table represents the scores from each participant in the geriatric depression scale (GDS) before and then after receiving the DBS treatment at the ventral capsule/ventral striatum.
Note: GDS score ? 9 means the patient is depressed.
Carry out the appropriate statistical test to determine if DBS is effective in reducing depression when stimulating the ventral capsule/ventral striatum. Write your null and alternative hypotheses and report the p-value to support your conclusion.
Before DBS After DBS 8 10 10 12 10Explanation / Answer
Solution:
Null Hypothesis (Ho): µD ? 0
Alternative Hypothesis (Ha): µD < 0
D-bar = 3/5 = 0.6,
sD = sqrt(11.2/4) =1.673
Test Statistics
t = (D-bar - 0)/(sd/sqrt(n))
t = (0.6 - 0)/(1.673/sqrt(5))
t = -0.80
Degrees of freedom, df = n - 1= 5 - 1 = 4
Using t-tables, the p-value is
P [t (4) ? -0.80] = 0.2338
Since p-value is greater than the 0.05 significance level, we fail to reject Ho.
Hence, we cannot conclude that DBS is effective in reducing depression when stimulating the ventral capsule/ventral striatum.
Before DBS After DBS D = After- Before D - D-bar (D - D-bar)^2 9 8 -1 -1.6 2.56 10 9 -1 -1.6 2.56 9 10 1 0.4 0.16 9 12 3 2.4 5.76 10 11 1 0.4 0.16 Sum = 3 11.2Related Questions
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