Part 1: Preparing data for analysis.
You are a research assistant in a study of cardiovascular disease (CVD) and its risk factors. This study has conducted a survey of the prevalence of CVD and its risk factors. The data were collected using a paper-based questionnaire and the results have been typed into a computer file. Your task is to prepare the dataset for analysis by the study statistician. A description of the data set is in the word document:
assignment part 1 data description
What is your main task in preparing the data set for analysis?
Prepare the data set and state what you did and how you modified the dataset.
The data are in the comma separated file cvd_study.csv
These are synthetic data, but you may refer to the source of these data as ‘assignment 3: cvd study’.
Part 2: A study of systolic blood pressure.
You are conducting a study of systolic blood pressure. You have a data set for 500 people with a measure of systolic blood pressure before and after an intervention. You have also collected information on your study subjects’ coffee drinking and cigarette smoking. The description of the variables on this data set are in the word document:
assignment part 2 data description
Subject’s systolic blood pressure was measured using a mercury sphygmomanometer with the subject in a seated position and the arm flexed. Cigarettes smoked per day and habitual number of coffee cups consumed per day were self-reported. The average caffeine content of a cup of coffee (40 ml) is approximately 100mg. The mean number of coffee cups consumed per day was 5.3 (SD 3.2) and the mean number of cigarettes smoked per day was 6.5 (SD 5.8).
The data were collected in such a way as to ensure that they are statistically independent.
You are interested in whether or not the blood pressure lowering intervention had a measurable effect on mean systolic blood pressure. You are also interested in a possible effect of coffee drinking on blood pressure.
The data are in the comma separated file sysbp_study.csv
These are synthetic data, but you may refer to the source of these data as
‘assignment 3: sysbp study’.
1. The effect of the intervention
Conduct a test of whether or not blood pressure changed from before to after the intervention based on the mean systolic blood pressure. You should report and interpret the effect size and confidence interval as well as hypothesis test results. (10 marks)
2. The effect of coffee on high blood pressure
Using the ratio, test whether the risk of high blood pressure before the intervention differs between people who do drink coffee and people who don’t drink coffee. You should report and interpret the effect size and confidence interval as well as hypothesis test results. (6 marks)
3. Coffee and smoking
3.1 You are concerned that a potential relationship between coffee and smoking may influence your results. Can you carry out a chi square test to see if there is a relationship between coffee drinking and smoking? Note – I’m not actually asking you to carry out the chi square test – just to tell me if it would be valid in this data set. (1 mark)
3.2 Is there evidence that coffee intake in cups and number of cigarettes are linearly related?