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Mr Azaza in the Department of Kinesiology at the University of Alberta conducted study on the effectiveness of Yoga on Body Mass Index? (BMI)

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Mr Azaza in the Department of Kinesiology at the University of Alberta conducted study on the effectiveness of Yoga on Body Mass Index? (BMI). The study was published in the International Journal of Yoga in? 2017, and the results were widely covered in the media. The following is from the abstract of the? study:
?Background:
?Yoga, an ancient Indian system of exercise and therapy is an art of good living or an integrated system for the benefit of the? body, mind, and inner spirit. Regular practice of yoga can help to increase blood flow to the? brain, reduce? stress, have a calming effect on the nervous? system, and greatly help in reducing hypertension.
?Aim:
Aim of the present study is to evaluate the effect of? 1-month yoga practice on body mass index? (BMI), and blood pressure? (BP).
Materials and? Methods:
The present study was conducted to determine the effect of yoga practice on 66 participants ? (treatment group) whereas the results were compared with 24 healthy volunteers? (control group). We examined the effects of yoga on physiological parameters in a? 1-month pilot study. Most of the participants were learner and practiced yoga for 1 hour daily in the morning for 1 month. BMI and BP? (systolic and? diastolic) were studied before and after 1 month of yoga practice.
?Results:
Yoga practice causes decreased BMI? (-1.18), systolic BP? (-3.39 mmHg), and diastolic BP? (-2.4 mmHg). On the other? hand, no significant changes were observed in BMI and BP of control group.
?Conclusion:
This study concludes that yoga practice has potential to control BMI and BP without taking any medication.
The treatment group was drawn from volunteers from a pool of participants who had enrolled in a? 1-month free yoga program offered at the University of Alberta. When asked why they enrolled in the Yoga? program, the typical response was that they were interested in a? 'healthy lifestyle' or to? 'meet people.' The control group was drawn from 24 students at the University of Alberta who did not enrol in the free yoga program. These students responded to an ad posted in the main concourse on campus. The reward for the control group was a? $10 gift certificate for Tim? Horton's. The study was funded by The Central Council for Research in Yoga? & Naturopathy.
Denote the treatment variable by
Upper X Subscript i
?,
which can take on values of 1? (enrolled in? Yoga) or 0? (Not enrolled in? Yoga).  
Out of 90? students, 66 of them practiced yoga for? 1-month. The outcome variable is an? individual's change in BMI over the? 1-month period, denoted by
Upper Y Subscript i
.
The professor considers the regression? model:
Upper Y Subscript i Baseline equals beta 0 plus beta 1 times Upper X Subscript i Baseline plus u Subscript i What does u Subscript i ?mean?


A.
Is a? constant, and has an expected value? = 0
B.
u contains unobserved factors about people that determines whether they practice yoga
C.
is low for people who typically practice yoga
D.
u Subscript nothing



contains unobserved factors about people that affects their BMI aside from Yoga practice
The professor assumes that
Upper E left parenthesis u Subscript i Baseline | Upper X Subscript i Baseline right parenthesis equals 0
.
We can interpret this? as:


A.
u Subscript nothing



is? as-good-as randomly assigned
B.
This is just a normalisation since the professor includes a constent in the regression.
C.
unobserved factors are not all that important.
D.
Those who practice Yoga are on average the same as those who do not practice Yoga
The Sample regression is
ModifyingAbove Upper Y Subscript i with caret equals 0.01 minus 1.18 times Upper X Subscript i
What is the overal sample mean of the change in? BMI?


A.
0.01
B.
?-1.17
C.
?-0.85
D.
?-1.18
Suppose that a participant in the treatment group had an observed change in BMI of? -1.5. What is this persons? residual?


A.
?-2.67
B.
?-.33
C.
?-.30
D.
?-.32
The authors calculate that
Var left parenthesis Upper Y Subscript i Baseline right parenthesis equals 1
.
Calculate the? t-statistic that the difference in means between the two groups is zero under the assumption of homoskedasticity.


A.
?-4.908
B.
?-11.010
C.
There is not enough information to calculate the? t-statistic
D.
?-4.9504