Research has shown that losing even one night's sleep can have a significant effect on performance of complex tasks such as driving

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Research has shown that losing even one night's sleep can have a significant effect on performance of complex tasks such as driving. To demonstrate this phenomenon, a sample of n = 25 college students completed a driving test on a closed course at noon on one day and again at noon on the following day. The students were not permitted any sleep between the two tests. For each student, the difference between the number of errors on the first day and the number or errors on the second day was recorded. For this sample, the students averaged MD = 4.7 points less errors on the first test with a variance of s2 = 64 for the difference scores.
a)Do the data indicate a significant change in driving ability? Use a two-tailed test with = .05. (Use 3 decimal places.)
t-critical = ±
t =
b)What is the appropriate conclusion? Write A, B, C, or D in the box.
Option A. Reject the null hypothesis, losing one night's sleep does not have a significant effect on performance.
Option B. Reject the null hypothesis, losing one night's sleep does have a significant effect on performance.
Option C. Fail to reject the null hypothesis, losing one night's sleep does not have a significant effect on performance.
Option D. Fail to reject the null hypothesis, losing one night's sleep does have a significant effect on performance.
C) Compute an estimated Cohen's d to measure the size of the effect. (Use 4 decimal places.)
d =
Calculate the difference scores and find MD for the following data from a repeated-measures study. (Solve for the blanks)
Subject Treatment 1 Treatment 2 D
A 12 14 Blank 1
B 7 15 Blank 2
C 10 8 Blank 3
D 8 12 Blank 4
MD =
A researcher obtains a t statistic of t = 2.00 from a repeated measures study using n = 17 participants. If the effect size is measured using r2, what value will be obtained for r2?
a. r2 = 4/16 = 0.25
b. r2 = 4.00
c. The value of r2 cannot be determined from the information provided.
d. r2 = 4/20 = 0.20
In a repeated-measures study comparing two treatments, what boundaries has the two-tailed critical region for the t statistic with = .05 and a sample of n = 12 participants?
a. t =(plus-minus sign) 2.228
b. t =(plus-minus sign) 1.796
c. t =(plus-minus sign) 1.812
d. t =(plus-minus sign) 2.201

• 6 years ago