In: Statistics and Probability
Is the average time to complete an obstacle course different when a patch is placed over the right eye than when a patch is placed over the left eye? Thirteen randomly selected volunteers first completed an obstacle course with a patch over one eye and then completed an equally difficult obstacle course with a patch over the other eye. The completion times are shown below. "Left" means the patch was placed over the left eye and "Right" means the patch was placed over the right eye.
Right | 48 | 44 | 46 | 48 | 41 | 41 | 45 | 50 |
---|---|---|---|---|---|---|---|---|
Left | 45 | 39 | 45 | 45 | 41 | 38 | 44 | 49 |
Assume a Normal distribution. What can be concluded at the the αα = 0.01 level of significance level of significance?
For this study, we should use Select an answer: z-test for the difference between two population proportions, z-test for a population proportion, t-test for the difference between two independent population means, t-test for the difference between two dependent population means, or t-test for a population mean
H0: Select an answer p1 μd μ1 Select an answer > < ≠ = Select an answer p2 μ2 0 (please enter a decimal)
H1: Select an answer p1 μd μ1 Select an answer > = ≠ < Select an answer 0 μ2 p2 (Please enter a decimal)
* NOTE: Ignore the “thirteen” I think it’s a typo. This is a matched pair (dependent) hypothesis test so you will run the test on the differences This is the 2 sample that once you take the differences it becomes a single sample test run on the differences.
*** Please print or type clearly. Thank you so much
, t-test for the difference between two dependent population means
Sample #1 | Sample #2 | difference , Di =sample1-sample2 | (Di - Dbar)² |
48 | 45 | 3.00 | 0.77 |
44 | 39 | 5.00 | 8.27 |
46 | 45 | 1.00 | 1.27 |
48 | 45 | 3.00 | 0.77 |
41 | 41 | 0.00 | 4.52 |
41 | 38 | 3.00 | 0.77 |
45 | 44 | 1.00 | 1.27 |
50 | 49 | 1.00 | 1.27 |
sample 1 | sample 2 | Di | (Di - Dbar)² | |
sum = | 363 | 346 | 17.000 | 18.875 |
Ho : µd= 0
Ha : µd ╪ 0
Level of Significance , α =
0.01 claim:µd=0
sample size , n = 8
mean of sample 1, x̅1= 45.375
mean of sample 2, x̅2= 43.250
mean of difference , D̅ =ΣDi / n =
2.125
std dev of difference , Sd = √ [ (Di-Dbar)²/(n-1) =
1.6421
std error , SE = Sd / √n = 1.6421 /
√ 8 = 0.5806
t-statistic = (D̅ - µd)/SE = (
2.125 - 0 ) /
0.5806 = 3.660
Degree of freedom, DF= n - 1 =
7
p-value = 0.0080 [excel function:
=t.dist.2t(t-stat,df) ]
Conclusion: p-value <α , Reject null
hypothesis
The results are statistically significant at αα = 0.01, so there is
sufficient evidence to conclude that the population mean time to
complete the obstacle course with a patch over the right eye is not
the same as the population mean time to complete the obstacle
course with a patch over the left eye...............
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THANKS
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