STAT Midterm CH. 1-13 Questions With Complete
Solutions
(b) An employer asks employees to participate in a research
study. Although the employer has assured employees that
participation is voluntary, several employees are concerned that
a decision to not participate could affect performance
evaluations or job advancement.
Does circumstance (b) constitute coercion? Explain your
reasoning. correct answers No, because the subject is not being
intentionally threatened to participate in the study.
(b) Is the type of tweet (liberal or conservative) a treatment
variable or a block? Why? correct answers Type of tweet is a
treatment variable because it can be randomly assigned to the
participants, after blocking.
(b) Make a diagram to describe the treatments. How many
treatments are there? correct answers 4
(b) The placebo was actually the hepatitis A vaccine and that
"hepatitis was not studied, but to keep the investigators from
knowing which colonies received the flu vaccine, they had to
offer placebo shots, and hepatitis shots do some good while
sterile water injections do not." In addition, the article mentions
that the colonies were studied "without the investigators being
subconsciously biased by knowing which received the placebo."
Which of the following is not a reason why it is important that
investigators not be subconsciously biased by knowing which
received the placebo? correct answers The investigators may
,choose to give the flu vaccine to the colonies that already appear
healthier.
(c) By June 2009, more than 10% of all the adults and children
in colonies that received the placebo had had
laboratory-confirmed seasonal flu. Less than 5%
of those in the colonies that received flu shots had. This
difference was statistically significant.
What does the term "statistically significant" mean in the
context of this study? correct answers The observed difference
in the percent of adults and children who had the flu between the
two groups is most likely due to the effect of the treatment, not
to chance variation.
(From the news) A Washington Post article reported that
psilocybin, the active ingredient of "magic mushrooms,"
promoted a mystical experience in two-thirds of people who
took it for the first time, according to a study published in the
online journal Psychopharmacology . The authors of the article
stated that their "double-blind study evaluated the acute and
longer-term psychological effects of a high dose of psilocybin
relative to a comparison compound administered under
comfortable, supportive conditions."
Complete the statement that correctly explains to someone who
knows no statistics what the term "double-blind" means in this
experiment. correct answers "Double-blind" means that
NEITHER THE SUBJECTS NOR RESEARCHERS knew
WHETHER PSILOCYBIN OR THE COMPARISON
COMPOUND WAS ADMINISTERED TO EACH SUBJECT
This method prevents potential bias caused by expectations that
THE SUBJECTS AND RESEARCHERS might have about
,WHETHER MUSHROOMS CAUSE MYSTICAL
EXPERIENCES
(From the news) On September 1, 2018, The Columbus
Dispatch reported on a study about political polarization and
social media. In this study, 901
Democrats and 751
Republicans were recruited. The Democrats were randomly
divided into two groups. All were asked to follow an automated
Twitter account (Twitter bot) each day for one month. One
group recieved tweets with a liberal point-of-view, and the other
tweets with a conservative point-of-view. Likewise, Republicans
were randomly divided into two groups and recieved the same
two treatments (liberal or conservative tweets). All subjects
were given a test, both before and after the experiment that
scored them on a liberal/conservative scale. Changes in scores
were the response variable.
(a) Is the political affiliation of the subjects (Democrat or
Republican) a treatment variable or a block? Why? correct
answers Political affiliation is a block because participants were
split on this factor initially before seeing the tweets.
A 72-year-old man with multiple sclerosis is hospitalized. His
doctor feels he may need to be placed on a feeding tube soon to
ensure adequate nourishment. He asks the patient about this in
the morning and the patient agrees. However, in the evening
(before the tube has been placed), the patient becomes
disoriented and seems confused about his decision to have the
feeding tube placed. He tells the doctor he does not want it in.
The doctor revisits the question in the morning when the patient
, is again lucid. Unable to recall his state of mind from the
previous evening, the patient again agrees to the procedure.
Do you believe the patient has given informed consent to the
procedure? correct answers Yes. The patient gave the consent
twice when he was lucid and only denied consent when he was
confused.
A clinical trial is correct answers an experiment to study the
effectiveness of medical treatments on actual patients.
A club has 30 student members and 10
faculty members. The students are
Student Members Aguirre Cooper Kemp Peralta Stankiewicz
Butterfield Dobbs Kessler Risser Steele Caporuscio Freeman
Koepnick Rodriguez Tong Carlson Girard Macha Ryndak White
Chilson Gonzales Makis Soria Williams Clement Grebe
Palacios Spiel Zhang
The faculty members are
Faculty Members Atchade Everson Hansen Nair Romero
Craigmile Fink Murphy Nguyen Turkmen
The club can send 3 students and 2 faculty members to a
convention. It decides to choose those who will go by random
selection.
What is the chance, 𝑃(White), that the student named White is
chosen? Give your answer as a percentage rounded to the
nearest whole number.
Solutions
(b) An employer asks employees to participate in a research
study. Although the employer has assured employees that
participation is voluntary, several employees are concerned that
a decision to not participate could affect performance
evaluations or job advancement.
Does circumstance (b) constitute coercion? Explain your
reasoning. correct answers No, because the subject is not being
intentionally threatened to participate in the study.
(b) Is the type of tweet (liberal or conservative) a treatment
variable or a block? Why? correct answers Type of tweet is a
treatment variable because it can be randomly assigned to the
participants, after blocking.
(b) Make a diagram to describe the treatments. How many
treatments are there? correct answers 4
(b) The placebo was actually the hepatitis A vaccine and that
"hepatitis was not studied, but to keep the investigators from
knowing which colonies received the flu vaccine, they had to
offer placebo shots, and hepatitis shots do some good while
sterile water injections do not." In addition, the article mentions
that the colonies were studied "without the investigators being
subconsciously biased by knowing which received the placebo."
Which of the following is not a reason why it is important that
investigators not be subconsciously biased by knowing which
received the placebo? correct answers The investigators may
,choose to give the flu vaccine to the colonies that already appear
healthier.
(c) By June 2009, more than 10% of all the adults and children
in colonies that received the placebo had had
laboratory-confirmed seasonal flu. Less than 5%
of those in the colonies that received flu shots had. This
difference was statistically significant.
What does the term "statistically significant" mean in the
context of this study? correct answers The observed difference
in the percent of adults and children who had the flu between the
two groups is most likely due to the effect of the treatment, not
to chance variation.
(From the news) A Washington Post article reported that
psilocybin, the active ingredient of "magic mushrooms,"
promoted a mystical experience in two-thirds of people who
took it for the first time, according to a study published in the
online journal Psychopharmacology . The authors of the article
stated that their "double-blind study evaluated the acute and
longer-term psychological effects of a high dose of psilocybin
relative to a comparison compound administered under
comfortable, supportive conditions."
Complete the statement that correctly explains to someone who
knows no statistics what the term "double-blind" means in this
experiment. correct answers "Double-blind" means that
NEITHER THE SUBJECTS NOR RESEARCHERS knew
WHETHER PSILOCYBIN OR THE COMPARISON
COMPOUND WAS ADMINISTERED TO EACH SUBJECT
This method prevents potential bias caused by expectations that
THE SUBJECTS AND RESEARCHERS might have about
,WHETHER MUSHROOMS CAUSE MYSTICAL
EXPERIENCES
(From the news) On September 1, 2018, The Columbus
Dispatch reported on a study about political polarization and
social media. In this study, 901
Democrats and 751
Republicans were recruited. The Democrats were randomly
divided into two groups. All were asked to follow an automated
Twitter account (Twitter bot) each day for one month. One
group recieved tweets with a liberal point-of-view, and the other
tweets with a conservative point-of-view. Likewise, Republicans
were randomly divided into two groups and recieved the same
two treatments (liberal or conservative tweets). All subjects
were given a test, both before and after the experiment that
scored them on a liberal/conservative scale. Changes in scores
were the response variable.
(a) Is the political affiliation of the subjects (Democrat or
Republican) a treatment variable or a block? Why? correct
answers Political affiliation is a block because participants were
split on this factor initially before seeing the tweets.
A 72-year-old man with multiple sclerosis is hospitalized. His
doctor feels he may need to be placed on a feeding tube soon to
ensure adequate nourishment. He asks the patient about this in
the morning and the patient agrees. However, in the evening
(before the tube has been placed), the patient becomes
disoriented and seems confused about his decision to have the
feeding tube placed. He tells the doctor he does not want it in.
The doctor revisits the question in the morning when the patient
, is again lucid. Unable to recall his state of mind from the
previous evening, the patient again agrees to the procedure.
Do you believe the patient has given informed consent to the
procedure? correct answers Yes. The patient gave the consent
twice when he was lucid and only denied consent when he was
confused.
A clinical trial is correct answers an experiment to study the
effectiveness of medical treatments on actual patients.
A club has 30 student members and 10
faculty members. The students are
Student Members Aguirre Cooper Kemp Peralta Stankiewicz
Butterfield Dobbs Kessler Risser Steele Caporuscio Freeman
Koepnick Rodriguez Tong Carlson Girard Macha Ryndak White
Chilson Gonzales Makis Soria Williams Clement Grebe
Palacios Spiel Zhang
The faculty members are
Faculty Members Atchade Everson Hansen Nair Romero
Craigmile Fink Murphy Nguyen Turkmen
The club can send 3 students and 2 faculty members to a
convention. It decides to choose those who will go by random
selection.
What is the chance, 𝑃(White), that the student named White is
chosen? Give your answer as a percentage rounded to the
nearest whole number.
