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McMaster: Health Sci essay: critical thinking

1,500 characters including spaces and punctuation

A wellness company claims its app cut users' stress by 40%, citing a study of 200 paying subscribers who reported feeling calmer after eight weeks. Before I trusted that number, I would ask who was left out. Paying subscribers who stayed eight weeks are exactly the people the app was already working for; everyone who quit in week two is invisible. There is no comparison group, so I cannot tell the app apart from time passing, the season changing, or simply expecting to feel better. Self-reported calm is also not the same as a measured stress marker. None of this proves the app fails. It proves the claim is not yet evidence. To believe the 40%, I would want a control group that never used the app, the dropouts counted, and an outcome measured rather than felt. The interesting question is not whether the app works. It is what would have to be true for that number to mean what it says.
What it’s really asking

A Question 2-style Health Sciences prompt: evaluate a claim, dataset, or proposal and reason through it. The program wants logical, structured critical thinking and clear judgment of evidence.

Why they ask it

Health Sciences trains students to handle data and arguments, so it screens for that thinking up front. This prompt tests whether you can spot weak evidence and reason about it cleanly, not whether you reach a particular verdict.

Three ways in
Name the specific flaw

Point to the actual problem (no control group, selection bias, self-report) rather than saying the claim is just wrong. Precision shows real analysis.

Stay fair

Say what the data does and does not show, instead of dunking on it. Measured judgment reads as maturity, not the loud skepticism graders see constantly.

Specify better evidence

End by stating what evidence would actually settle the question. That move proves you understand how a claim becomes evidence.

✕  Weak opening

“In today's data-driven world, it is more important than ever to think critically about the statistics we see.”

✓  Strong opening

“A wellness company claims its app cut users' stress by 40%, citing a study of 200 paying subscribers who reported feeling calmer after eight weeks.”

✦ Annotated example · The tutoring stat that proved nothing. Written by EssayLens to teach, not a real applicant’s essay. Tap a highlighted line →
A tutoring service advertises that students who use it raise their math grade by a full letter, citing 150 students who improved after a semester of sessions. 1Before I believed that, I would ask who is counted and who is missing. The 150 are students who kept paying and finished a semester, which means the ones who gave up or saw no progress and quit are not in the figure at all. 2There is also no comparison group. Students often improve from one semester to the next simply because the material clicks, a teacher changes, or they mature. Without students who did not tutor, I cannot separate the service from ordinary growth. 3And a letter grade is not a clean measure. Grades shift with easier units, generous marking, or extra credit, so a better grade does not have to mean better understanding. 4None of this means the tutoring is useless. It means the advertisement is a story, not yet evidence. 5To trust the claim, I would want students randomly assigned to tutoring or not, the quitters tracked, and learning measured on a shared test rather than by classroom grades. The useful question is not whether tutoring helps. It is what would have to be true for that letter grade to mean what the ad wants me to think it means.6
  1. 1Restates the claim cleanly with its specific numbers, mirroring the model and giving the reader a concrete target to scrutinize.
  2. 2Identifies survivorship bias in plain language. This is the central critical-thinking move and the essay leads with it.
  3. 3Raises the missing control group and names rival explanations. McMaster rewards thinking, so showing alternative causes matters more than a verdict.
  4. 4Questions the outcome measure itself, not just the sampling, which shows layered reasoning rather than one objection.
  5. 5Refuses a lazy gotcha and holds the careful distinction between unproven and false, signaling intellectual fairness.
  6. 6Ends by specifying what real evidence would look like and reframing the question, closing near the character limit with composure.
Stuck? Start here
  • Who or what is missing from this data, and how would that change the conclusion?
  • Is there a comparison group, or could something else explain the result?
  • What specific evidence would make me actually believe the claim?
Before you submit
  • I named specific flaws, not vague distrust of statistics.
  • I stayed fair about what the data does and does not show.
  • Under 1,500 characters including spaces and punctuation.

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