# Worked example: a transparent assignment description Version 1.0, August 2026. This is the description I hand out with Assignment 1 in EPI 501 (Principles and Methods of Epidemiology I), lightly edited. It is here so you can see what the blank template looks like when it is filled in, including the places where mine is still weaker than it should be. --- ## Assignment 1: Measures of Disease Frequency **Scenario.** You are a public health researcher tasked with analyzing the incidence, prevalence, and measures of comparison of a disease over a two-year period based on provided data. ### Purpose The purpose of this assignment is to enhance your understanding and application of fundamental epidemiologic measures such as incidence and prevalence. By completing this assignment you will gain the skills necessary to calculate and interpret these measures, which are crucial for analyzing public health data. It will also improve your ability to compare population groups on these measures, which is the foundation for the more advanced analysis later in the course. ### Skills and knowledge this builds - Applying epidemiologic methods, specifically incidence and prevalence calculations - Using a provided dataset to compute epidemiologic measures - Evaluating data to identify significant public health patterns - Summarizing and interpreting what an epidemiologic measure means - Connecting concepts from lecture and readings to an analysis ### Task **Before you start:** - Read this description and note any questions so we can clarify them in class. - Review the lectures and readings on incidence and prevalence. - Open the dataset and make sure you understand the variables and structure before computing anything. **What to do.** Begin by analyzing the provided data to compute the cumulative incidence of disease for each exposure group over the first two years of the study. Use the same data to calculate the prevalence of disease at the end of the first two years for each exposure group. Compare the cumulative incidence and the prevalence, and explain any differences or similarities, since this comparison is where most people go wrong. Next, calculate the risk difference and the risk ratio from your previous results, and interpret what each means in the context of this study. Compute the incidence rate for both exposure groups over the two-year period, then the incidence rate ratio, and explain its significance. Summarize your findings, interpreting the results in terms of their public health implications rather than restating the numbers. **What to hand in.** One page maximum, single spaced, 12-point Times New Roman, 1-inch margins. Include tables or figures as needed. Submit as PDF to the Brightspace assignment link by the due date. Use APA format for any citations. ### Criteria for success - Full points for correct and accurate calculations. - A small deduction for calculations that are directionally right but not fully accurate. - No points where the calculation is incorrect. --- ## What is good and what is not Worth copying: the purpose section says what the student will be able to do and where it is used later, rather than saying the assignment assesses understanding. The preparatory steps are specific about which materials to revisit. The task is written in the order the student will work, and it names the step people get wrong at the point where they will be doing it. Not worth copying: **the criteria section is the weakest part of this document.** Three lines about calculation accuracy do not tell a student what a good interpretation looks like, and interpretation is most of what the assignment is actually asking for. A student could compute everything correctly, write a poor summary, and have no way of predicting the grade. The fix is the three-tier table in `rubric-tiers-skeleton.md`, applied per component, with a row for interpretation and a row for the public health implications. I have not yet done that for this assignment. It is on the list, and I am leaving the flawed version visible here because a manual that only shows finished work is not much use for estimating how long things take.