Relabeling a beach survey's relative risk as a prevalence ratio is the central move in this HS340 Unit 3 study design appraisal example, argued from when each question was asked. Searches like "hs 340 unit 3 assignment example", "hs340 unit 3 sample" and "hs340 unit 3 example" land here.
What a finished HS340 Unit 3 study design appraisal looks like
Roughly four pages long, the appraisal opens with the study as its composite authors described it: one summer weekend, 1,100 adults interviewed once at the beach exit, 640 who had entered the water and 460 who had not. Gastrointestinal symptoms in the previous seven days were reported by 58 swimmers and 23 non-swimmers, 9.1 percent against 5.0. A short table restates those counts. The appraisal then classifies the design from its data collection rather than its title, calling it cross-sectional because exposure and outcome were measured at the same moment. It recomputes the result as a prevalence ratio of 1.81 with a prevalence difference of 4.1 points, identifies the week before the visit as a window that places some illness before any swim, and sketches the follow-up design that would permit risk.
How a HS340 Unit 3 example is structured
The appraisal answers three questions in a fixed order: what the study did, what design that makes it, and which measure the design is entitled to report. Description comes first and is kept free of judgment, so the classification that follows can be checked against it. Classification rests on timing. Every respondent was asked about exposure and symptoms in one conversation, and the symptom window reached back seven days, so some of the illness counted in swimmers began before they entered the water. That problem of order is the appraisal's center, and it is why the authors' relative risk becomes a prevalence ratio. Credit for what the design still does well keeps the critique fair. The close describes a cohort alternative: swimmers and non-swimmers enrolled at the beach and telephoned ten to twelve days later about new symptoms.
The study as reported
One weekend, one beach, one interview per person at the exit. Counts for swimmers and non-swimmers sit in a four-cell table, with the authors' own term for the design quoted once.
Design named by its timing
Exposure and outcome were recorded together, which makes the survey cross-sectional whatever its title says. The appraisal defines the term in a sentence and applies it to this collection method.
Illness that came before the swim
A seven-day recall window means a respondent sick on Tuesday who swam on Saturday counts as an ill swimmer. The appraisal names this as a failure of temporal order, not of arithmetic.
The measure the data can carry
Recent symptoms at 9.1 percent against 5.0 give a prevalence ratio of 1.81 and a difference of 4.1 points. The appraisal keeps the computation and changes only the label and the sentence reading it.
What one interview does well
Cheap, fast and able to reach a thousand people in a weekend, the survey is a reasonable way to raise a question about water quality. The appraisal credits that before recommending anything stronger.
What a follow-up call would add
Enrolling beachgoers before symptoms and calling them about new illness ten to twelve days later would fix the order of events and permit cumulative incidence, the base any risk ratio needs.
Where marks go in HS340 Unit 3
Appraisal rubrics in this course tend to reward correct design identification, a matched measure, and a defensible account of what threatens validity. The identification row is earned by reasoning from how data were gathered; a paper that repeats the authors' label, or classifies the study by whether it compared two groups, usually loses it. The measure row turns on whether the reported ratio survives the reclassification, and showing that the arithmetic stands while the name changes is how the example takes it. Validity marks go to a specific threat tied to a specific feature of the method, here the recall window. Deductions commonly follow a critique that says only that surveys rely on memory, a cohort declared without any follow-up period, and recommendations for a better study that never say what it would measure.
Get a HS340 Unit 3 example written to your instructions
For HS340 Unit 3, send the study description or article the prompt names, the appraisal questions in their order, and the grading rubric. Within 24-48 hours the free first custom sample classifies that study from its methods, states which measure it is entitled to report, and points to the sentence where the design's limit shows.
HS340 Unit 3 questions, answered
How can a design be classified when the authors call it something else?
Read the methods for timing. If exposure and outcome were measured at one point, the study is cross-sectional; if participants were selected by outcome, it is case-control; if people free of the outcome were followed forward, it is a cohort. Authors sometimes use cohort loosely. An appraisal that explains its classification from the data collection will be credited even when it disagrees with the title.
Is a prevalence ratio less useful than a relative risk?
It answers a different question. A prevalence ratio compares how common a condition is in two groups at one time, which is useful for planning and for raising hypotheses. It cannot show that exposure came first, and for short illnesses it mixes new and older cases. The beach example reports 1.81 honestly as a prevalence ratio and treats it as a lead worth testing properly.
Does the appraisal need to calculate anything?
Usually a little. Recomputing the headline figure from the supplied counts shows that the numbers are sound and that only the interpretation is in question, which is a strong position for a critique. The example recalculates both prevalences and the ratio in three lines, then spends the rest of its length on design, where most of the unit's marks sit.