Head movement evaluations are important because disabled individuals may be able

Question

Head movement evaluations are important because disabled individuals may be able to operate communications aids using head motion. A paper reported the accompanying data on neck rotation (in degrees) for 14 subjects both in the clockwise direction (CL) and in the counterclockwise direction (CO). For purposes of this exercise, you can assume that the 14 subjects are representative of the population of adult Americans.

Based on these data, is it reasonable to conclude that mean neck rotation is greater in the clockwise direction than in the counterclockwise direction? Carry out a hypothesis test using a significance level of 0.01. (Use a statistical computer package to calculate the P-value. Use CL CO. Round your test statistic to two decimal places and your P-value to three decimal places.)

t =

df =

P-value =

Im not sure what I'm doing wrong, I got, s1= 10.8, s2=10.25, mean1=46.15, mean2=54.85 and my answers for t and df are wrong. I got t = .33 and df = 25.9

Subject: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 CL: 57.3 35.7 54.5 56.8 51.1 70.8 77.3 51.6 54.7 63.6 59.2 59.2 55.8 38.5 CO: 44.6 52.1 60.2 52.7 47.2 65.6 71.4 48.8 53.1 66.3 59.8 47.5 64.5 34.1

Explanation / Answer

Since the same subjects has been measured, this would be a dependent sample. The statistical software output for this problem is:

Paired T hypothesis test:
D = 1 - 2 : Mean of the difference between CL and CO
H0 : D = 0
HA : D > 0
Hypothesis test results:

Hence,

t = 0.63

df = 13

P - value = 0.271

Difference Mean Std. Err. DF T-Stat P-value CL - CO 1.3 2.0740945 13 0.62677953 0.2708

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