A study found that children who regularly eat breakfast perform better academically than those who frequently skip it. Researchers concluded that eating breakfast directly improves cognitive function in children, leading to higher grades. Which of the following, if true, would most seriously undermine the researchers' conclusion?
- ASome breakfast foods contain high levels of sugar, which can lead to a sugar crash later in the morning.
- BChildren who eat breakfast regularly tend to come from families with higher socioeconomic status, who also provide more overall academic support.
- CAcademic performance is a complex measure influenced by many factors beyond diet.
- DThe study was observational and did not involve a controlled experimental group.
Show answer & explanationAnswer & explanation
Correct answer: B. Children who eat breakfast regularly tend to come from families with higher socioeconomic status, who also provide more overall academic support.
The conclusion claims a direct causal link between eating breakfast and cognitive function. Option A introduces a confounding variable (socioeconomic status and academic support) that could be the true underlying cause of both regular breakfast eating and better academic performance, thus undermining the direct causal claim.
Why the other options are wrong
- A. This points to a potential negative aspect of some breakfasts but doesn't undermine the general claim that 'eating breakfast' improves cognitive function.
- C. This is a general statement that doesn't provide a specific alternative explanation for the observed correlation, unlike option A.
- D. While true for observational studies, this is a methodological limitation, not a specific factor that undermines the conclusion itself by offering an alternative cause.
Confounding Variable
A confounding variable is an unmeasured third variable that influences both the supposed cause and the supposed effect, creating a spurious correlation and making it seem like there's a direct causal link when there isn't.
- Creates a false impression of causality.
- Must be correlated with both the independent and dependent variables.
- Often explains away an apparent causal relationship.
Memory trick: A hidden actor pulling strings, making two unrelated puppets dance together.