A researcher would like to test the effect of a new diet drug on the activity le

Question

A researcher would like to test the effect of a new diet drug on the activity level of animals. A sample of n = 16 rats is obtained & each rat’s activity level is measured on an exercise wheel for one hour prior to receiving the drug. Thirty minutes after receiving the drug, each rat is again tested on the activity wheel. The data show that the rats increased their activity by an average of MD = 21 revolutions with SSD= 6000 after receiving the drug. Do these data indicate that the drug had a significant effect on activity? Use a two-tailed test with ? = 0.05.

he null hypothesis (H0) is:

Question 9 options:

µD ? 0

µD = 0

µD ? 21

µD = 21

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Question 10 (0.5 points)

The alternative hypothesis (H1) is:

Question 10 options:

µD ? 21

µD = 21

µD ? 0

µD = 0

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Question 11 (0.5 points)

The degrees of freedom (df) are:

Question 11 options:

df = 14

df = 15

df = 16

df = 17

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Question 12 (0.5 points)

The tcritical values are:

Question 12 options:

tcritical = ±2.131

tcritical = ±1.753

tcritical = ±2.120

tcritical = ±1.746

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Question 13 (0.5 points)

What is the variance of the difference scores (s2D)?

Question 13 options:

s2D = 375    

s2D = 428.57

s2D = 400   

s2D = 352.94

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Question 14 (0.5 points)

What is the estimated standard error for the sample mean difference (SMD)?

Question 14 options:

SMD = 5.16   

SMD = 4.84

SMD = 5.35

SMD = 5

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Question 15 (0.5 points)

What is the t-statistic?

Question 15 options:

t = 4.20   

t = 4.34

t = 4.07   

t = 3.93

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Question 16 (0.5 points)

What is the conclusion?

Question 16 options:

Fail to reject H0: The drug had a significant effect on activity.

Fail to reject H0: The drug did NOT have a significant effect on activity.

Reject H0: The drug had a significant effect on activity.

Reject H0: The drug did NOT have a significant effect on activity.

A)

µD ? 0

B)

µD = 0

C)

µD ? 21

D)

µD = 21

Explanation / Answer

9)
null hypothesis contains equality
hence
B)   

µD = 0 is correct

10)
since we want to check if the drug had a significant effect on activity
it is two-sided test

C)   

µD ? 0 is correct

11)
df = n-1 = 16-1 = 15
B) is correct

12)
t-critical for df = 15 , alpha = 0.05
=t.inv.2t(0.05,15)   {in excel}
=2.131449546

A) 2.13 is correct

13)
variance = SS_d/(n-1) = 6000/15 =400
14)
standard error = sd/sqrt(n) = sqrt(400)/sqrt(16)
= 20/4 = 5

15)
t-stat = (Xbar -mu)/se
= (21 - 0)/5
= 4.2

16)
since TS > critical value

C) Reject H0: The drug had a significant effect on activity.

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