LSAT (Law School Admission Test)Logical ReasoningEasy
A recent study found that individuals who regularly consume whole grains have a significantly lower risk of heart disease than those who do not. A nutritionist concludes that increasing whole grain consumption is an effective way to prevent heart disease. \n\nWhich of the following, if true, most seriously weakens the nutritionist's conclusion?
- AMany people who regularly consume whole grains also engage in other healthy lifestyle practices, such as regular exercise and avoiding smoking.
- BSome types of whole grains are more difficult for the body to digest than refined grains.
- CThe study only included participants from one geographic region, which has a generally lower incidence of heart disease.
- DHeart disease can also be caused by genetic factors, which were not accounted for in the study.
Show answer & explanationAnswer & explanation
Correct answer: A. Many people who regularly consume whole grains also engage in other healthy lifestyle practices, such as regular exercise and avoiding smoking.
The nutritionist concludes that whole grain consumption causes a lower risk of heart disease. Option A introduces an alternative explanation for the observed correlation, suggesting that other healthy habits, rather than solely whole grains, might be responsible for the lower heart disease risk, thus weakening the causal link.
Why the other options are wrong
- B. Difficulty in digestion is a different issue and does not directly contradict the claim that whole grain consumption prevents heart disease.
- C. While limiting the study's generalizability, this doesn't directly weaken the causal link between whole grains and heart disease within the studied population.
- D. While genetic factors contribute to heart disease, the study focuses on lifestyle choices. This option doesn't undermine the potential preventative effect of whole grains in individuals susceptible to heart disease.
Confounding Variable
An extraneous variable in a statistical model that correlates (directly or inversely) with both the dependent and independent variables, potentially leading to a spurious association.
- Can obscure or exaggerate a true relationship.
- Must be controlled for in experimental design or statistical analysis.
- Often explains an apparent causal link when none truly exists.
Memory trick: Look for a hidden link that breaks the chain.