A deficiency of the trace element selenium in the diet can negatively impact growth, immunity, muscle and neuromuscular function, and fertility. The introduction of selenium supplements to dairy cows is justified when pastures have low selenium levels. Authors of a research paper supplied the following data on milk selenium concentration (mg/L) for a sample of cows given a selenium supplement (the treatment group) and a control sample given no supplement, both initially and after a 9-day period. Initial Measurement Treatment Control 11.4 9.1 9.6 8.7 10.1 9.7 8.5 10.8 10.2 10.9 10.6 10.6 11.9 10.1 9.9 12.3 10.7 8.8 10.2 10.4 10.3 10.9 11.4 10.4 9.3 11.6 10.6 10.9 10.9 8.3  After 9 Days Treatment Control 138.3 9.2 104 8.9 96.4 8.9 89 10.1 88 9.6 103.8 8.6 147.3 10.4 97.1 12.4 172.6 9.2 146.3 9.5 99 8.4 122.3 8.8 103 12.5 117.8 9.1 121.5 93   (a) Use the given data for the treatment group to determine if there is sufficient evidence to conclude that the mean selenium concentration is greater after 9 days of the selenium supplement. (Use ? = 0.05. Use ?d = ?initial − ?9-day.) Find the test statistic. (Round your answer to two decimal places.) t =  Find the df. df =   Use technology to find the P-value. (Round your answer to four decimal places.) P-value =   State your conclusion. Reject H0. We do not have convincing evidence that the mean selenium concentration is greater after 9 days of the selenium supplement.Reject H0. We have convincing evidence that the mean selenium concentration is greater after 9 days of the selenium supplement.    Fail to reject H0. We have convincing evidence that the mean selenium concentration is greater after 9 days of the selenium supplement.Fail to reject H0. We do not have convincing evidence that the mean selenium concentration is greater after 9 days of the selenium supplement. (b) Are the data for the cows in the control group (no selenium supplement) consistent with the hypothesis of no significant change in mean selenium concentration over the 9-day period? (Use ? = 0.05. Use ?d = ?initial − ?9-day.) Find the test statistic. (Round your answer to two decimal places.) t =  Find the df. df =   Use technology to find the P-value. (Round your answer to four decimal places.) P-value =  State your conclusion. Fail to reject H0. We do not have convincing evidence that the mean selenium concentration for cows in the control group changed significantly over the 9-day period.Reject H0. We have convincing evidence that the mean selenium concentration for cows in the control group changed significantly over the 9-day period.    Fail to reject H0. We have convincing evidence that the mean selenium concentration for cows in the control group changed significantly over the 9-day period.Reject H0. We do not have convincing evidence that the mean selenium concentration for cows in the control group changed significantly over the 9-day period. (c) Would you use the paired t test to determine if there was a significant difference in the initial mean selenium concentration for the control group and the treatment group? Explain why or why not. Yes, the paired t test would be appropriate because the sample differences can be viewed as a random sample from a population of differences, the treatment and control groups were paired samples, and we can assume the sample differences come from a normally distributed population of differences.No, the paired t test would not be appropriate because the number of sample differences is not large enough and the population distribution of differences is positively skewed.     Yes, the paired t test would be appropriate since the treatment and control groups were paired samples.No, the paired t test would not be appropriate since the treatment and control groups were not paired samples.

Calculus For The Life Sciences
2nd Edition
ISBN:9780321964038
Author:GREENWELL, Raymond N., RITCHEY, Nathan P., Lial, Margaret L.
Publisher:GREENWELL, Raymond N., RITCHEY, Nathan P., Lial, Margaret L.
Chapter1: Functions
Section1.2: The Least Square Line
Problem 8E
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A deficiency of the trace element selenium in the diet can negatively impact growth, immunity, muscle and neuromuscular function, and fertility. The introduction of selenium supplements to dairy cows is justified when pastures have low selenium levels. Authors of a research paper supplied the following data on milk selenium concentration (mg/L) for a sample of cows given a selenium supplement (the treatment group) and a control sample given no supplement, both initially and after a 9-day period.
Initial Measurement
Treatment Control
11.4 9.1
9.6 8.7
10.1 9.7
8.5 10.8
10.2 10.9
10.6 10.6
11.9 10.1
9.9 12.3
10.7 8.8
10.2 10.4
10.3 10.9
11.4 10.4
9.3 11.6
10.6 10.9
10.9
8.3
 
After 9 Days
Treatment Control
138.3 9.2
104 8.9
96.4 8.9
89 10.1
88 9.6
103.8 8.6
147.3 10.4
97.1 12.4
172.6 9.2
146.3 9.5
99 8.4
122.3 8.8
103 12.5
117.8 9.1
121.5
93
 
(a)
Use the given data for the treatment group to determine if there is sufficient evidence to conclude that the mean selenium concentration is greater after 9 days of the selenium supplement. (Use ? = 0.05. Use ?d = ?initial − ?9-day.)
Find the test statistic. (Round your answer to two decimal places.)
t = 
Find the df.
df =  
Use technology to find the P-value. (Round your answer to four decimal places.)
P-value =  
State your conclusion.
Reject H0. We do not have convincing evidence that the mean selenium concentration is greater after 9 days of the selenium supplement.Reject H0. We have convincing evidence that the mean selenium concentration is greater after 9 days of the selenium supplement.    Fail to reject H0. We have convincing evidence that the mean selenium concentration is greater after 9 days of the selenium supplement.Fail to reject H0. We do not have convincing evidence that the mean selenium concentration is greater after 9 days of the selenium supplement.
(b)
Are the data for the cows in the control group (no selenium supplement) consistent with the hypothesis of no significant change in mean selenium concentration over the 9-day period? (Use ? = 0.05. Use ?d = ?initial − ?9-day.)
Find the test statistic. (Round your answer to two decimal places.)
t = 
Find the df.
df =  
Use technology to find the P-value. (Round your answer to four decimal places.)
P-value = 
State your conclusion.
Fail to reject H0. We do not have convincing evidence that the mean selenium concentration for cows in the control group changed significantly over the 9-day period.Reject H0. We have convincing evidence that the mean selenium concentration for cows in the control group changed significantly over the 9-day period.    Fail to reject H0. We have convincing evidence that the mean selenium concentration for cows in the control group changed significantly over the 9-day period.Reject H0. We do not have convincing evidence that the mean selenium concentration for cows in the control group changed significantly over the 9-day period.
(c)
Would you use the paired t test to determine if there was a significant difference in the initial mean selenium concentration for the control group and the treatment group? Explain why or why not.
Yes, the paired t test would be appropriate because the sample differences can be viewed as a random sample from a population of differences, the treatment and control groups were paired samples, and we can assume the sample differences come from a normally distributed population of differences.No, the paired t test would not be appropriate because the number of sample differences is not large enough and the population distribution of differences is positively skewed.     Yes, the paired t test would be appropriate since the treatment and control groups were paired samples.No, the paired t test would not be appropriate since the treatment and control groups were not paired samples.
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