Do wearable devices that monitor diet and physical activity help people lose weight? Researchers had 237 subjects, already involved in a program of diet and exercise, use wearable technology for 24 months. They measured their weight (in kilograms) before using the technology and 24 months after using the technology.   (a) Explain why the proper procedure to compare the mean weight before using the wearable technology and 24 months after using the wearable technology is a matched pairs t test. Choose the correct explanation.   A) A person's weight before and after wearing the device would not be independent; thus, the data from this before and after study should not be analyzed using a matched pairs ?t test.   B) A person's weight before and after wearing the device would be independent; thus, the data from this before and after study should be analyzed using a matched pairs ?t test.   C) A person's weight before and after wearing the device would be independent; thus, the data from this before and after study should not be analyzed using a matched pairs ?t test.   D) A person's weight before and after wearing the device would not be independent; thus, the data from this before and after study should be analyzed using a matched pairs ?t test.     (b) The 237 differences in weight (weight after 24 months minus weight before using the wearable technology) are x¯=−3.5 and s=7.8 . Let μ be the mean weight difference (weight after 24 months minus weight before using the wearable technology).   Complete the test to see if there is significant evidence of a reduction in weight after using the wearable technology.   What is the correct null and alternative hypothesis? Select an answer choice.   A) H0:μ<0 versus Ha:μ=0 B) H0:μ=0 versus Ha:μ≠0 C) H0:μ=0 versus Ha:μ<0 D) H0:μ>0 versus Ha:μ<0     What is the test statistic t ? (Enter your answer rounded to three decimal places.)   t=     What is the P‑value? Select an answer choice.   A) P>0.05 B) P<0.0001 C) P=0.0001 D) P>0.01     Select the correct interpretation of the results based on your analysis.   A) There is an extreme amount of evidence that there is a decrease in average weight after wearing the device.   B) There is an extreme amount of evidence that there is an increase in average weight after wearing the device.   C) There is a small amount of evidence that there is a decrease in average weight after wearing the device.   D) There is an not enough evidence that there is a decrease in average weight after wearing the device.

Glencoe Algebra 1, Student Edition, 9780079039897, 0079039898, 2018
18th Edition
ISBN:9780079039897
Author:Carter
Publisher:Carter
Chapter10: Statistics
Section10.3: Measures Of Spread
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Do wearable devices that monitor diet and physical activity help people lose weight? Researchers had 237 subjects, already involved in a program of diet and exercise, use wearable technology for 24 months. They measured their weight (in kilograms) before using the technology and 24 months after using the technology.
 
(a) Explain why the proper procedure to compare the mean weight before using the wearable technology and 24 months after using the wearable technology is a matched pairs t test. Choose the correct explanation.
 
A) A person's weight before and after wearing the device would not be independent; thus, the data from this before and after study should not be analyzed using a matched pairs ?t test.
 
B) A person's weight before and after wearing the device would be independent; thus, the data from this before and after study should be analyzed using a matched pairs ?t test.
 
C) A person's weight before and after wearing the device would be independent; thus, the data from this before and after study should not be analyzed using a matched pairs ?t test.
 
D) A person's weight before and after wearing the device would not be independent; thus, the data from this before and after study should be analyzed using a matched pairs ?t test.
 
 
(b) The 237 differences in weight (weight after 24 months minus weight before using the wearable technology) are x¯=−3.5 and s=7.8 . Let μ be the mean weight difference (weight after 24 months minus weight before using the wearable technology).
 
Complete the test to see if there is significant evidence of a reduction in weight after using the wearable technology.
 
What is the correct null and alternative hypothesis? Select an answer choice.
 
A) H0:μ<0 versus Ha:μ=0
B) H0:μ=0 versus Ha:μ≠0
C) H0:μ=0 versus Ha:μ<0
D) H0:μ>0 versus Ha:μ<0
 
 
What is the test statistic t ? (Enter your answer rounded to three decimal places.)
 
t=
 
 
What is the P‑value? Select an answer choice.
 
A) P>0.05
B) P<0.0001
C) P=0.0001
D) P>0.01
 
 
Select the correct interpretation of the results based on your analysis.
 
A) There is an extreme amount of evidence that there is a decrease in average weight after wearing the device.
 
B) There is an extreme amount of evidence that there is an increase in average weight after wearing the device.
 
C) There is a small amount of evidence that there is a decrease in average weight after wearing the device.
 
D) There is an not enough evidence that there is a decrease in average weight after wearing the device.
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