Reference no: EM132301136
Biostatistics Assignment Questions -
Read the following data description and answer questions 1 to 3.
The table below presents the results of a clinical trial to test the effectiveness of a new drug and existing drug in reducing the duration of symptoms for malaria. One sample of patients was given drug 1 and another sample was given drug 2. Both samples had their symptom duration recorded. The aim is to see if the new treatment (drug 2) leads to a different duration of symptoms than the existing drug (drug 1).
The samples have been selected so that the data are statistically independent.
|
Drug 1
|
Drug 2
|
|
Patient number
|
Duration of malaria symptoms (days)
|
Patient number
|
Duration of malaria symptoms (days)
|
|
1
|
13.39
|
1
|
10.36
|
|
2
|
13.96
|
2
|
9.59
|
|
3
|
13.18
|
3
|
9.65
|
|
4
|
14.66
|
4
|
10.64
|
|
5
|
15.11
|
5
|
12.03
|
|
6
|
13.78
|
6
|
10.45
|
|
7
|
13.44
|
7
|
9.75
|
|
8
|
13.85
|
8
|
9.09
|
|
9
|
12.21
|
9
|
8.46
|
|
10
|
13.89
|
10
|
10.83
|
|
11
|
14.24
|
11
|
10.23
|
|
12
|
13.43
|
12
|
9.24
|
|
13
|
15.28
|
13
|
11.4
|
|
14
|
15.39
|
14
|
8.9
|
|
15
|
14.72
|
15
|
9.46
|
|
16
|
12.09
|
16
|
11.15
|
|
17
|
12.03
|
17
|
10.14
|
|
18
|
13.43
|
18
|
10.45
|
|
19
|
13.16
|
19
|
10.91
|
|
20
|
14.13
|
20
|
10.19
|
|
21
|
14.48
|
21
|
10.07
|
|
22
|
14.92
|
22
|
9.53
|
|
23
|
15.54
|
23
|
8.77
|
These are synthetic data, but you may reference them in your answers as coming from assignment 2 data: test of malaria symptom duration.
These data are in the file assignment 2 duration data.csv.
1. Calculate an estimate and 95% confidence interval for the mean malaria symptom duration for each of drug 1 and drug 2. Cite your answers to 1 decimal place.
As part of this answer you should:
a. Specify which probability distribution you will use and demonstrate why you can use it with these data (hint: you should use qnorm plots here).
b. Cite the estimates and confidence intervals to 1 decimal place.
c. Give an interpretation of the confidence intervals in words.
2. What do these confidence intervals tell you about the mean symptom duration for drug 1 and drug 2?
3. Test the hypothesis that the mean symptom duration for drug 1 is different to the mean symptom duration for drug 2, stating the test statistic to 1 decimal place. As part of your answer you should:
a. State what is the appropriate statistical test to use and why.
b. Correctly report and interpret the results of the hypothesis test.
c. Can repeat the t-test from question 1 or refer to it.
4. A randomised control trial tests the effectiveness of a new intervention in reducing hospital length of stay for patients with a given disease that requires surgery. The hospital length of stay (days) was recorded and the value (cost) of length of stay estimated in AUD before the intervention and after the intervention. The hospitalisation cost data consists of a sample of 220 and 3 variables - personal ID (pid), cost before (before) and cost after (after). The data is in a spreadsheet called hospitalisation cost.csv. These are synthetic data, but you may reference them in your answers as coming from assignment 2 data: hospitalisation cost.
a. Calculate the appropriate estimate of the mean hospitalisation cost and its associated 95% confidence interval before the intervention and after the intervention. Include your stata commands and results.
b. Using evidence from the mean and associated 95% confidence interval, does our data provide any evidence whether the new intervention made a difference to the average hospitalisation cost?
5. Victorian children aged 6 months to five years were offered free influenza shots following the devastating flu season in 2017. In 2018, a random sample of 1000 children visiting a GP in Victoria were asked about whether or not they took up the offer of a free vaccine. The data set assignment 2 vaccination data.csv contains the variable vaccinated which takes the value vaccinated = 1 if the child took up the offer of free vaccine; and vaccinated = 0 if they did not.
a. What is the proportion of children that received the free vaccination? Give answer to 2 decimal places.
b. What is the associated 95% confidence interval? Give answer to 2 decimal places. As part of your answer state what probability distribution, you use to calculate this and why you can use it.
Note - Some of the questions require calculations using Stata. Where you have used Stata for calculations, you should copy the Stata commands and output from the Stata results screen and paste them into your assignment so that the assessor can see how you have derived your answer. Note: this Stata output is required in addition to your answer to the question. Simply pasting in the Stata output will not be considered an adequate answer on its own.
Attachment:- Assignment Files.rar