Unit 8 · Detecting Reasoning Errors

Ms Vega's Sugary Drinks Study — Spot the Flaw

Lesson 9 of 10

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About this lesson

Detecting Reasoning Errors is the largest and most diverse question category in OC TS — with 122 questions covering a wide range of logical flaws. Let's start with the most commonly tested and most intuitively accessible error: concluding that because two things happen together, one must be causing the other.

Chapters

0:00Introduction
0:24The Question
1:18Strategy
1:51Step 1: Name the flaw
2:18Step 2: The hidden cause (confounding factor)
2:55Step 3: Pick the option
3:40Correct answer

Question

Ms Vega notices that students in her class who regularly drink sugary drinks at lunch have lower test scores on average than those who don't.

She concludes: "Sugary drinks are causing students to perform worse on tests."

Which sentence best shows the mistake in Ms Vega's reasoning?

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