John Hay
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Genetics of Disease (Medical Interventions)
Unit 1: How to Fight InfectionMI 1.1Biotechnology Research & Experiments (BRE)

Building an outbreak claim from multiple evidence sources

Make a claim-evidence-reasoning argument supported by independent lines of evidence, not a single clue.

Builds on (2 levels back)inferred · med confidence
  • Claim-Evidence-Reasoning (CER): The benchmark is a CER argument; students need the CER frame first.
  • Correlation vs. causation: A strong claim needs converging evidence, not one coincidence.

Prerequisites are inferred: pending teacher review.

Re-learn the skill with worked practice and clear examples.

The strongest scientific claim is the one supported by several independent lines of evidence that point the same way.

Step 1: Gather the lines
In an outbreak: who got sick, what they shared (a meal, a place), the timing, the symptom pattern, and lab results.
Step 2: Look for convergence
A claim gets strong when independent clues agree: shared meal AND matching symptoms AND timing AND a lab match.
Step 3: Reject the weak options
'Most common answer,' 'a guess,' or 'test everyone' are not evidence-based claims.
Practice

Four students fell ill the same evening. All four ate Tuesday's cafeteria meal and all had the same symptoms (vomiting and cramps); a fifth student who did not eat the meal stayed well (see the diagram). Which conclusion is best supported as a scientific claim about this foodborne outbreak?

Approved
Network diagram: a central 'Cafeteria meal, Tue' node links to four patient nodes who are ill; a fifth person who did not eat there is unconnected and well.
  1. A.It is the most common answer, so it is probably right
  2. B.The four cases share a meal, a matching symptom pattern, and similar onset timing
  3. C.We should just guess based on the first patient
  4. D.We should test every person in the city
Show the worked solution ▾

Answer: B. The four cases share a meal, a matching symptom pattern, and similar onset timing

  1. Step 1: Read the figure: The diagram shows all four ill students linked to the same Tuesday meal, while the student who skipped it stayed well.
  2. Step 2: Count independent lines: Shared meal (diagram) + the same symptoms + the same evening onset (stem) = three converging clues, not one.
  3. Step 3: Reject non-evidence: 'Most common,' 'guess,' and 'test everyone' are not evidence-based claims.

Why it's right: A claim backed by several independent, converging lines of evidence is the strongest: that is the benchmark.

Why the others miss:
  • A: Popularity is not evidence.
  • C: A guess from one case ignores the converging data.
  • D: Testing everyone is not a claim and isn't feasible or targeted.

Aligned to BRE: evidence-based claim (benchmark) · reading level ~grade 9

Where you'd see this
  • A public-health report that names a source only after exposure data, symptom data, and lab data agree.
Careers that use this
Epidemiologist: Names an outbreak source only when independent evidence lines converge.
Video library
Prerequisite: Claim-Evidence-Reasoning
CER - Claim Evidence Reasoning
Bozeman Science · 7:26
Prerequisite: correlation vs. causation
The danger of mixing up causality and correlation
TEDx Talks · 5:42
Remediation: how outbreaks are investigated
Outbreaks - investigation and control
Global Health with Greg Martin
Extension: case-control & confounders
Case-control study explained
Henrik's Lab
Guided notes

Fill these in as you work through the lesson.

Big idea: A strong scientific claim about an outbreak rests on several independent lines of evidence that point the same way: not one coincidence.
Key terms: write the meaning
  • Claim (your answer):  
  • Evidence (the data):  
  • Reasoning (why the data backs the claim):  
  • Confounder (a tangled second cause):  
The rule

In CER, the   is your answer, the   is the data, and the   explains why the data supports the answer. A claim is strongest when several   clues agree.

Check yourself
  1. Why is one shared clue (everyone ate at the cafeteria) not enough to name the source? 
  2. Name three of the lines of evidence an outbreak investigator looks for. 
  3. When two exposures are tangled together (like a shared meal and a shared bus), what kind of new fact would help you tell which one is the real cause? 
Work one example

Four students got sick and all ate Tuesday's cafeteria meal; one student who did not eat it stayed well. Write it as CER: start: 'Claim: the Tuesday meal was the source. Evidence: ____. Reasoning: ____.'