Worked from one composite school district's asthma table, the PU520 Unit 2 problem set example computes prevalence and incidence several ways and names the denominator behind every answer. Searches like "pu 520 unit 2 assignment example", "pu520 unit 2 sample" and "pu520 unit 2 example" land here.
What a finished PU520 Unit 2 epidemiology problem set looks like
Numbered problems fill about four pages, preceded by the supplied table restated in full: 18,000 enrolled pupils on September 1, 1,530 with active asthma on that date, 214 new diagnoses during the school year, and 15,900 child-years at risk after transfers in and out. Problem 1 gives point prevalence, 8.5 percent. Problem 2 computes cumulative incidence over the 16,470 pupils free of asthma at the start, about 13.0 per 1,000. Problem 3 adds the new cases to the old for a period prevalence of 9.7 percent. Problem 4 divides by child-years for 13.5 per 1,000 child-years, and Problem 5 explains why that figure and the cumulative one differ. Problem 6 applies the steady-state relation between prevalence, incidence and duration, with the assumptions it needs spelled out.
How a PU520 Unit 2 example is structured
Every problem shares one layout: the question restated, the formula in words, the numbers substituted, the answer with its multiplier and unit, and one sentence on what the figure means for the district. Repeating it six times is a choice, since a grader marking six answers can find the setup in the same place each time. Denominators get harder as the set goes on. Point prevalence uses everyone enrolled. Cumulative incidence removes the 1,530 children who already had asthma, since a child with the condition cannot become a new case, and the example says so in a full sentence. Person-time comes later because it requires accepting that children enter and leave the at-risk pool mid-year. The final problem ties the three measures together and ends on the limitation that a school population is never truly in steady state.
The supplied table, restated
All four inputs appear in one small table before Problem 1, each labeled with the date or period it describes. Restating them catches misread figures early, and graders can trace every later answer back to a cell.
Removing children already counted
The cumulative incidence problem shows 18,000 minus 1,530 before dividing. A single sentence explains that the population at risk excludes existing cases, which is the correction most often missing from submitted work.
Child-years instead of children
Transfers mean some pupils were observed for part of the year only. The example explains how 15,900 child-years were accrued and why the rate that uses them compares more fairly with other districts.
Duration from two measures
Rearranging the steady-state relation gives an average duration of roughly seven years. The example flags the answer as approximate and lists the assumptions a real district would violate.
Answers with multipliers attached
Every result carries its scaling, per 1,000 pupils or per 1,000 child-years, and its period. No answer appears as a bare decimal, and percentages are used only for the two prevalence figures.
Where marks go in PU520 Unit 2
Problem sets in this course tend to be marked on setup as much as on the final number, and rubrics in many sections award working, accuracy and interpretation separately. The example earns setup credit by writing the formula in words before substituting, so a wrong arithmetic step would still show a correct method. Accuracy marks turn on the denominator. A frequent deduction on this unit is cumulative incidence divided by the whole enrollment instead of the pupils at risk, small enough to slip past most writers. Next come prevalence and incidence confused in the question that asks for new cases, a rate reported without its time unit, and person-time treated as a head count. Interpretation marks go to the closing sentence of each problem, where a school nurse would learn what the figure means.
Get a PU520 Unit 2 example written to your instructions
Send the table your PU520 Unit 2 problem set supplies, along with the questions as written and the rubric. The desk works every problem in the layout shown here, formula in words first. That first custom sample is free, delivered inside 24-48 hours, and it explains each denominator at the point where a grader would look for it.
PU520 Unit 2 questions, answered
Should the problem set show hand calculations or only answers?
Show the working. Most PU520 problem sets reward setup, and a grader who can see the formula and the substituted numbers can award partial credit when an arithmetic slip creeps in. The example writes each formula in words, then in numbers, then gives the answer with its multiplier. Spreadsheet formulas can sit in an appendix where a section asks for them.
What is the difference between cumulative incidence and an incidence rate?
Cumulative incidence is a proportion: new cases over the people at risk when a period begins. An incidence rate divides new cases by person-time, so it handles people who join or leave partway through. In the asthma example the two come to 13.0 and 13.5 per 1,000, because transfers shortened the time some pupils were observed.
Why is the duration answer only approximate?
The formula linking prevalence, incidence and duration assumes a population in steady state, with stable rates and little movement in or out. A school district breaks that assumption every year as classes graduate and new pupils enroll. The example reports roughly seven years and says plainly that the figure illustrates the relationship instead of measuring how long childhood asthma lasts.