Question

A medical researcher would like to determine how effective a new
form of knee surgery is for

treating knee pains. (In particular, is there a relationship
between surgery status and pain

reduction status?) He gathers 500 people with knee pain who are
scheduled to have this

surgery, and 500 people with knee pain who are not scheduled to
have this surgery. He follows

up with both groups after 2 months and determines the number of
participants of each group

who report a “significant reduction in knee pain”. He summarizes
his findings in the table

below:

Contingency Table Pain Reduction Status

Pain Reduction No Pain Reduction

Surgery Status Surgery 340 160

No Surgery 280 220

(a) (2 points) Between a t-test, a χ

2

-test, and an F-test, which is the most appropriate for

this study?

(b) (1 point) State the hypotheses for this test.

(c) (1 point) What is/are the conditions(s) for this test to be
valid?

(d) (1 point) Are the conditions for this test satisfied? (Yes /
no)

(e) (3 points) The researcher finds a test statistic of 15.65 and a
p-value of 0.0001. Interpret

this p-value. (Hint: 0.0001 is the probability of...)

(f) (1 point) Based on a significance level of 0.001, should we
reject or fail to reject H0?

(g) (1 point) Is this an experiment or an observational
study?

(h) (1 point) If this is an experiment, is this study single-blind,
double-blind, or neither? If

this is not an experiment, leave this question blank.

(i) (1 point) If this is an experiment, is this a randomized
controlled trial? If this is not an

experiment, leave this question blank

(j) (1 point) If this is an observational study, is it
prospective or retrospective? If this is not

an observational study, leave this question blank.

(k) (1 point) If this is an observational study, is it case-control
or cohort? If this is not an

observational study, leave this question blank.

(l) From prior experience, the medical researcher thinks that about
35% of new surgeries he

tests are effective in pain reduction. Suppose this researcher
conducts 100,000 of these

tests (for all different surgeries), at a significance level of
0.001 and a power of 0.55.

i. (1 point) When H0 is true, what is the probability of rejecting
H0 for these tests?

ii. (1 point) When H0 is false, what is the probability of
rejecting H0 for these tests?

iii. (2 points) For this test, what is a Type I error, and what is
a Type II error?

iv. (2 points (bonus)) What is the overall (average) error
rate?

v. (1 point (bonus)) Amongst all rejections of H0, what is the
(average) error rate?

vi. (1 point (bonus)) Amongst all failures to reject H0, what is
the (average) error rate?

vii. (1 point (bonus)) In these 100,000 tests, how many Type I
errors (on average) are

made?

(m) The researcher also wants to estimate the proportion of
surgery recipients who report pain

reduction after two months. In the sample of 500, 340 report pain
reduction after two

months, so ˆp = 64%.

i. (1 point) What is the population of interest for this confidence
interval?

ii. (1 point) It is thought that between 200,000 and 300,000 people
will receive this

surgery. Is a finite population correction appropriate here?

iii. (2 points) The researcher calculates a 2.14% margin of error
for his desired 95% con-

fidence interval, without a finite population correction. Use this
to construct the 95%

confidence interval, including the FPC if appropriate.

iv. (1 point) The researcher claims that this interval has a 95%
probability of containing

p. Is this correct?

v. (1 point) The researcher’s friend says that the researcher was
mistaken, and that the

interval in fact only has a 95% probability of containing ˆp. Is
his friend correct?

vi. (2 points) Suppose the researcher would like to have a margin
of error of only 1%.

What is the minimum sample size required to obtain this
result?

vii. (2 points) Confidence intervals for p require the distribution
of ˆp to be (approximately) normal. What do we call the
distribution of a sample statistic, such as ˆp?

What do we call the standard deviation of the distribution of a
sample statistic?

(n) (2 points) The researcher is deciding between three
different sampling techniques. Rank

these sampling techniques from least biased to most biased.

A. The researcher obtains a list of all patients scheduled to have
this surgery in the next

12 months. He then picks 500 names from this list randomly.

B. The researcher travels to the most expensive hospital in the
area. He then picks the

next 500 patients scheduled to receive this surgery.

C. The researcher puts up fliers around local malls, shopping
centres, grocery stores, gas

stations, hospitals, and universities, advertising his study. He
then picks the first 500

respondents to his fliers that qualify for the study

Answer #1

A. Chi square test is most appropriate.

B. H_{0}: Status of knee pain and surgery are
independent

C. A key assumption of the chi square test of independence is that each subject contributes data to only one cell. Therefore the sum of all cell frequencies in the table must be the same as the number of subjects in the experiment.

D. This assumption is satisfied in this situation.

E. 0.0001 is the probability of observing a test statistic as
extreme as *15.65,* assuming the null hypothesis is
true.

F. Based on significance level 0.001, we reject H_{0}.
Because p value is less than significance level.

G. This is an experiment.

H. This is neither single blind nor double blind.

A medical researcher wants to determine whether there is a
difference in the mean length of time it takes three types of pain
relievers to provide relief from headache pain. Several headache
sufferers are randomly selected and given one of the three
medications. Each headache sufferer records the time (in minutes)
it takes the medication to begin working. The results are shown in
the table. At a α = 0.01, can you conclude that the mean times are
different? Assume...

****PLEASE ANSWER ALL QUESTIONS****
Question 12 (1 point)
A medical researcher wants to determine if the average hospital
stay of patients that undergo a certain procedure is greater than
8.7 days. The hypotheses for this scenario are as follows: Null
Hypothesis: μ ≤ 8.7, Alternative Hypothesis: μ > 8.7. If the
researcher takes a random sample of patients and calculates a
p-value of 0.0942 based on the data, what is the appropriate
conclusion? Conclude at the 5% level of significance....

A medical researcher wants to determine if the average hospital
stay of patients that undergo a certain procedure is greater than
9.1 days. The hypotheses for this scenario are as follows: Null
Hypothesis: μ ≤ 9.1, Alternative Hypothesis: μ > 9.1. If the
researcher takes a random sample of patients and calculates a
p-value of 0.2003 based on the data, what is the appropriate
conclusion? Conclude at the 5% level of significance.
Question 5 options:
1)
The true average hospital...

In a cognitive psychology experiment, the researcher is
interested in whether encoding condition has an effect on memory
for a list of words. She recruits 16 subjects to participate in the
experiment. Each subject comes to the lab twice to be tested in two
different encoding conditions and their memory performance scores
are listed below. The researcher would like to leave the hypothesis
non-directional without predicting which encoding condition would
lead to better memory, and she sets the significance level...

21. A client who was admitted with pneumonia was complaining of
abdominal pain from frequent non- productive coughing. When he does
produce sputum, it is watery and yellowish-green. Which of the
following are appropriate nursing interventions at this time?
Select all that apply
Give him a pillow for splinting
Administer antitussive syrup, 30mg ordered prn.
Place him in appropriate positions for postural drainage
Encourage him to increase his oral fluid intake
Request an order for increasing flow rate.
22. A...

Using the model proposed by Lafley and Charan, analyze how
Apigee was able to drive innovation.
case:
W17400
APIGEE: PEOPLE MANAGEMENT PRACTICES AND THE CHALLENGE OF
GROWTH
Ranjeet Nambudiri, S. Ramnarayan, and Catherine Xavier wrote
this case solely to provide material for class discussion. The
authors do not intend to illustrate either effective or ineffective
handling of a managerial situation. The authors may have disguised
certain names and other identifying information to protect
confidentiality.
This publication may not be...

What tools could AA leaders have used to increase their
awareness of internal and external issues?
???ALASKA AIRLINES: NAVIGATING CHANGE
In the autumn of 2007, Alaska Airlines executives adjourned at
the end of a long and stressful day in the
midst of a multi-day strategic planning session. Most headed
outside to relax, unwind and enjoy a bonfire
on the shore of Semiahmoo Spit, outside the meeting venue in
Blaine, a seaport town in northwest
Washington state.
Meanwhile, several members of...

ADVERTISEMENT

Get Answers For Free

Most questions answered within 1 hours.

ADVERTISEMENT

asked 28 minutes ago

asked 46 minutes ago

asked 49 minutes ago

asked 50 minutes ago

asked 51 minutes ago

asked 1 hour ago

asked 1 hour ago

asked 1 hour ago

asked 1 hour ago

asked 2 hours ago

asked 2 hours ago

asked 2 hours ago