Understanding Clinical Research Behind the Statistics

In this blog you will find the correct answer of the Coursera quiz Understanding Clinical Research Behind the Statistics mixsaver always try to brings best blogs and best coupon codes
 

 

 

Week- 1

Peer-graded Assignment: Week 1: Navigating Clinical Research

 

Click Here To Download

 

Week 2 Graded Quiz

1.
Question 1
In a questionnaire, patients are asked to rate their opinion to a statement with a ‘1’ referring to not agreeing at all, to a ‘5’ referring to total agreement. Twenty patients complete the survey and the results are tabulated under a variable named ‘Responses to statement ‘.

What is an appropriate data type for this variable?

1 point

2.
Question 2
What best describes continuous data?

1 point

3.
Question 3
This and the following few questions pertains to the article: Amoxicillin plus temocillin as an alternative empiric therapy for the treatment of severe hospital-acquired pneumonia: results from a retrospective audit

In this article the authors were concerned about the outcome of patients admitted with severe hospital acquired pneumonia. This refers to severe bacterial infection of the lungs. The patients were infected whilst in hospital. Bacteria that exist in the hospital environment are usually more difficult to treat due to resistance of the bacteria to antibiotics. Patients who contract hospital acquired bacterial infections may have a worse outcome than those who contract bacterial infection in the community (outside the hospital). These patients are in hospital for a specific medical reason, which usually means that their ability to fight infection might be compromised. Hospital-acquired bacteria can also be more virulent. It is this combination of a weakened immune system and aggressive, difficult to treat bacteria that lead to a worse outcome.

In the healthcare setting pertaining to this setting a decision was made to change the standard antibiotic therapy for the treatment of patients with severe hospital-acquired pneumonia. These are difficult decisions to make due to the fact that it may directly impact the wellbeing of patients. A retrospective audit was conducted to assess the effect of this change.

What type of research was conducted in this study?

1 point

4.
Question 4
Suppose a study is planned to compare the effectiveness of the two types of antibiotics by selecting 100 patients and randomly assigning 50 of them to receive a new antibiotic number and the other 50 to receive the antibiotic used routinely. Both the patients and the medical personnel (including those who evaluate the treatment and collect the data) are blinded as to which antibiotic the patients receive until after the results of the analysis is available.

What is this type of study?

1 point

5.
Question 5
Data point values were collected pertaining to the variable, length of hospital stay. These values were captured in terms of days.

What data type does this represent?

1 point

6.
Question 6
Standard deviation is used to describe the spread in the data point values for age. What does this represent?

1 point

7.
Question 7
The actual data points that made up the possible values for the variable Clinical Outcome were: cure, failure, relapse, and intermediate.

What data type are these?

1 point

8.
Question 8
By what measure of central tendency would you express the data point values for the variable Clinical Outcome?

1 point

9.
Question 9
Researchers are interested in the use of screening mammography and it’s efficacy in preventing mortality from breast cancer. They form two groups of patients, pre- and post-menopausal. Patient files from a radiology unit were used in this study and included all patients seen in the last year.

What is the sampling strategy appropriate in this study for distinguishing between these two groups?

1 point

10.
Question 10
Researchers require 20 patients for their analysis of a new drug. Sixty equally suitable volunteers signed up to be part of the study. Every third volunteer on the list was selected to make up the sample.

What is the sampling strategy appropriate in this study?

1 point

 

 

Week 3 Graded Quiz

 

1.
Question 1
Read the article linked here: http://www.samj.org.za/index.php/samj/article/view/9298/6855

The researchers were concerned that the reference values for common blood cell counts used by South African laboratories were taken from research conducted on samples taken from population that did not reflect (could not be inferred to) the local population.

Answer this question and those that follow.

What type of study was this?

1 point

2.
Question 2
The method of dispersion used to describe the age variable in this study was the range. What does range refer to?

1 point

3.
Question 3
The blood samples were stored at 20 degrees Celsius, with a standard deviation of 4 degrees Celsius. If the data point values were normally distributed, with no statistical outliers, what does this imply?

1 point

4.
Question 4
In Table 1 the (median) values for the first variable, RBCs (red blood cells), is expressed in cells (times 10 to the power 12) per liter of blood. What data type value is represented here?

1 point

5.
Question 5
The measure of central tendency used to describe the number of each cell type is the median. Consider the distribution of the actual data point values.

1 point

6.
Question 6
To be entered into the study, participants had to be healthy. One of the criteria for classification as healthy was no prescribed medication (the baby / child should not be on any medication). If the data entry tool identified children that were not on medication as 0 (zero) and those on medication as 1 (one). Identify the data type for this variable.

1 point

7.
Question 7
Consider a possible follow-up study to this research, in which the same children were to be re-evaluated in five and again in 10 years. In the follow-up study researchers looked at their educational success and rates of certain illnesses. What study type would this represent.

1 point

8.
Question 8
The participants in this cross-sectional study were taken from the health clinics in one of the numerous informal settlements around a large city. What sampling technique would be describe this selection.

1 point

9.
Question 9
A p-value:

Multiple options are correct. Please select all that apply.

1 point

10.
Question 10
If there are five equally possible outcomes to an experiment, which are marked, in order, A, B, C, D, and E, what is the probability of finding a result of either D or E?

1 point

 

Week- 4

Peer-graded Assignment: Week 4 Peer review

 

Click Here To Download

 

 

Week 5 Graded Quiz

 

1.
Question 1
This and the following questions pertains to this article (the same paper used in a previous graded quiz) :

Full article link: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4514907/ or Link to PDF

In this paper the authors were concerned about the outcome of patients admitted with severe hospital acquired pneumonia. This refers to severe bacterial infection of the lungs. The patients were infected whilst in hospital. Bacteria that exist in the hospital environment are usually more difficult to treat due to resistance of the bacteria to antibiotics. Patients who contract hospital acquired bacterial infections may have a worse outcome than those who contract bacterial infection in the community (outside the hospital). These patients are in hospital for a specific medical reason, which usually means that their ability to fight infection might be compromised. Hospital-acquired bacteria can also be more virulent. It is this combination of a weakened immune system and aggressive, difficult to treat bacteria that lead to a worse outcome.

Consider the Materials and methods section. What type of test was used to compare continuous data types?

1 point

2.
Question 2
Which of the following was assumed when deciding to use Student’s t-test as one of the statistical analysis?.

1 point

3.
Question 3
Under the assumptions of a normal distribution of the required variable in the population from which a sample of participants are taken (as well as all other assumptions), which parametric test would be appropriate if the study design included self-controls?

1 point

4.
Question 4
If the investigators added a third group, using yet another antibiotic regime and this new group still met the criteria for the use of parametric tests, which test should be used instead of Student’s t-test?

1 point

5.
Question 5
Consider the question above (the investigators adding a third group, using yet another antibiotic regime). Which would be an appropriate test for comparing numerical data point values if the assumptions for the use of a parametric test are not met?

1 point

6.
Question 6
The study mentioned above found no statistical difference between the mean ages of the two antibiotic groups (table 1 on page 1695). The mean age of the newer antibiotic group (piperacillin/tazobactam) was 79 years and that of the other groups was 80 years. If the Student’s t-test referred to a two-tailed p-value, what would the alternative hypothesis be stated as?

1 point

7.
Question 7
Consider the duration of antibiotic treatment (in days) for the two groups (table 1 page 1695). The mean number of treatment days for the piperacillin/tazobactam group was 6.7 +- 1.6 days. How should we interpret the plus/minus 1.6 days?

1 point

8.
Question 8
If, instead of the standard deviation, confidence intervals were used for expressing the length of treatment (in days), how would you interpret the following result? The mean length of treatment for severe hospital-acquired pneumonia with piperacillin/tazobactam is 6.7 days (95% confidence interval 6.0 to 7.4 days.

1 point

9.
Question 9
Researchers quoted a p-value of 0.02 for the difference in effect of two drugs. What is the correct interpretation of a p-value?

1 point

10.
Question 10
Researchers find a strong positive correlation between alcohol intake and the incidence of hernia recurrence in patients who have undergone inguinal (groin) hernia repairs (p-value = 0.049, significance level 0.05). Which one of the following statements do you agree with?

1 point

 

 

Week 6 Final examination

 

1.
Question 1
This scenario refers to question 1, 2 and 3.

A research paper states the following in the Methods and Materials section: “Cohorts of an equal number of participants (60 in each group) were taken from each of the three units and tasked with completing the survey. Participants were allowed to choose a single answer from the seven-point Likert choices following each statement.”

Further along in the Results section they mention:

“Question 2 of the survey shows a statistically significant difference between the three groups.”

What type of research would you consider this to have been?

1 point

2.
Question 2
Pertaining to the research above.

What was the data type of the data point values compared to reach this significant difference between the groups?

1 point

3.
Question 3
Pertaining to the research mentioned in the previous question, what type of sampling did the researchers employ?

1 point

4.
Question 4

The following scenario refers to questions 4, 5, 6, 7 and 8.

The figure below is indicated in the Results section of a research paper. It identified four groups of patients and illustrates their analysis of the patients’ white cell counts. The researchers used a standard antibiotic drug and three novel (new) antibiotics, administered to patients admitted with bacterial pneumonia. The values below were taken from blood samples taken 24 hours after the start of treatment.

What type of plot is displayed in the figure above?

1 point

5.
Question 5
Pertaining to the research above, which of the following would be an appropriate measure of dispersion of the white cell count data point values?

1 point

6.
Question 6
Pertaining to the research above, indicate which of the four groups showed the biggest discrepancy between their mean (average) and median white cell count values.

1 point

7.
Question 7
Considering research to identify the most appropriate antibiotic, which of the following study types should be chosen to minimize the risk of bias and confounding?

1 point

8.
Question 8
Pertaining to the research above, it was found that patients receiving the standard drug had an average length of hospital stay of 6.7 days versus 5.9 days for the novel antibiotic groups (p = 0.04). For a chosen significance value of 0.05, what can be deduced from this result? Please choose the most appropriate answer.

1 point

9.
Question 9
The following scenario refers to questions 9 and 10.

Suppose one of the novel (new) antibiotics becomes approved for commercial use. A researcher wants to compare it’s efficacy in reducing patient temperature compared to the standard antibiotic drug used in their setting. The null hypothesis states that there is no difference in the average temperature on day 3 between the two antibiotics. Which is the correct alternative hypothesis?

1 point

10.
Question 10
Pertaining to the research above, it was shown that the data point values for one of the groups were not taken from a population in which the variable values are normally distributed. Which test would you have chosen to compare the white cell count of the four groups to each other?

1 point

11.
Question 11
The following scenario applies to question 11 and 12.

Researchers identified four groups of participants and compared the concentration of a certain drug in the blood stream of those participants and correlated it to the level of a certain hormone. Consider the following four graphs which appears in the Results section of their paper:

Which of the four graphs (groups A, B, C, or D) indicate the strongest inverse correlation between drug concentration and hormone level?

1 point

12.
Question 12
In considering the previous research paper, what type of statistical analysis would most likely have been used to compare the drug and hormone levels in the blood streams of the participants?

1 point

13.
Question 13

A study finds the mean cholesterol lowering capability of drug A as 2.0 mmol/L (95% CI 1.5 to 2.5 mmol/L) and that of drug B as 2.5 mmol/L (95% CI of 1.8 to 3.2 mmol/L).

Which of the following statements would you agree with?

1 point

 

14.
Question 14

The following scenario refers to questions 14 and 15.

Participants in the research above all took drug A for 4 weeks and were tested. This was followed by a period of abstinence for a minimum of 4 weeks before commencing a 4 week cycle on drug B. In comparing the mean (average) cholesterol levels between drugs A and B, which would be an appropriate statistical test?

1 point

15.
Question 15
The design of the study was altered to randomly assign two groups to either drug A or drug B. A large difference was found between the mean (average) and the median cholesterol levels (omitting any outliers) of these two groups, which would be an appropriate test to compare the two groups?

1 point

16.
Question 16

The following scenario refers to questions 16 and 17.

The following is noted in the Results section of a paper. A questionnaire was sent to trainees in a surgery department. For the particular set of questions indicated, participants could rate their agreement to statements on scale of 1 (do not agree at all) to 5 (totally agree).

Pertaining to the research above, which statistical test would you advise for comparing the choices of the groups of trainees for this question.

1 point

17.
Question 17
Pertaining to the research above, for a different section of the survey, the following contingency table was shown:

Trainees A Trainees B
Choice A 3 6 9
Choice B 4 4 8
7 10 17
Considering this table, what is the most appropriate test?

1 point

18.
Question 18
The following scenario pertains to questions 18, 19 and 20.

A study looked at the results of four tests to diagnose acute calculous cholecystitis (infection of the gallbladder due to gallstones). PPV and NPV indicate positive and negative predictive value respectively. A table in the Results section shows the following:

Test Sensitivity Specificity PPV NPV
A 90.0 85 35.0 90.0
B 91.0 60 23.5 91.0
C 85.4 65 45.0 93.5
D 60.0 94 31.0 98.0
Tasked with choosing the test that would correctly indicate most patients with the disease, which would you pick?

1 point

19.
Question 19
Pertaining to the research above, the tests seem to have a high sensitivity, but a low positive predictive values. Which of the following could be a possible cause for this discrepancy?

1 point

20.
Question 20
Suppose we consider a test with a very high sensitivity (i.e. test A) to test a patient for the presence of a disease and the result from the laboratory is negative. Which one of the following statements is true?

1 point