Biostatistics Exercise 1
The following data give systolic blood pressure measurements in mmHg taken immediately before and 2 hours after the drug captopril.
statistics problems with solutions and answers
Enter the data as 3 columns into jamovi, either directly or via Excel, and label.
- Convert the measurement data to Continuous measurement type.
- Obtain a descriptive summary for each of the 2 variables: Before and After. Give n, mean, SD, minimum, maximum.
- Do not use the Patient variable in any of the analyses. Why do we need it?
- Obtain histograms and box plots for each of the 2 variables.
- Select Correlation Matrix from the Regression menu in the Analyses Obtain a correlation and p value for Before and After variables. Add a sentence summarizing the analysis, including the kind of relationship between Before and After.
- Explain why the relationship seen is not surprising.
- From the Exploration menu do a scatterplot, putting Before on the X-axis and After on the Y-axis.
- Carry out a regression of After against Before.
- Select Model Coefficients and 95% Confidence interval Estimate.
- Select Assumption Checks and do Residual plots and Q-Q plot of residuals.
- Summarise fully the results of the regression analysis, including comments on the assumption checks.
- With a calculator or Excel, use the regression coefficients to obtain the predicted systolic blood pressure after the drug for a patient who had a blood pressure of 180 mmHg before the drug.
- Use jamovi to carry out a t test to examine the difference between Before and After. Summarize the results of your analysis and include a plot showing the difference between the two times.