People with a certain medical condition tend to have lower levels of low-density lipoprotein cholesterol (LDL-C) before they are diagnosed...
GMAT Critical Reasoning : (CR) Questions
People with a certain medical condition tend to have lower levels of low-density lipoprotein cholesterol (LDL-C) before they are diagnosed with this condition than do people without this condition. This association is equally strong whether or not the individuals have taken medications to lower their LDL-C. Therefore, having taken such medications does not make it more likely that people with lower LDL-C will develop the condition in question.
The doctor's argument is most vulnerable to criticism on which of the following grounds?
Passage Analysis:
Text from Passage Analysis People with a certain medical condition tend to have lower levels of low-density lipoprotein cholesterol (LDL-C) before they are diagnosed with this condition than do people without this condition.
- What it says: People who will get this medical condition already have lower LDL-C levels before getting diagnosed
- What it does: Sets up the basic observation about this medical condition
- What it is: Study finding/observation
- Visualization: Healthy people: LDL-C = 120, People who develop condition: LDL-C = 90 (before diagnosis)
This association is equally strong whether or not the individuals have taken medications to lower their LDL-C.
- What it says: The pattern of lower LDL-C stays the same regardless of whether people took cholesterol medications
- What it does: Adds important detail that medication use doesn't change the basic observation
- What it is: Additional study finding
- Visualization: With meds: Healthy = 100, Future patients = 70; Without meds: Healthy = 120, Future patients = 90 (same gap exists)
Therefore, having taken such medications does not make it more likely that people with lower LDL-C will develop the condition in question.
- What it says: Taking cholesterol medications doesn't increase your chances of getting this condition
- What it does: Draws a conclusion from the previous observations about medication and LDL-C levels
- What it is: Author's conclusion
Argument Flow:
The argument starts with an observation about LDL-C levels, adds detail showing this pattern exists regardless of medication use, then concludes medications don't cause the condition
Main Conclusion:
Taking LDL-C lowering medications does not make it more likely that people with lower LDL-C will develop this medical condition
Logical Structure:
The argument uses correlation data (lower LDL-C occurs with the condition regardless of medication) to conclude there's no causal relationship between medications and developing the condition. However, this reasoning confuses correlation with causation and doesn't account for alternative explanations
Prethinking:
Question type:
Misc. - This is asking us to find the biggest flaw or weakness in the doctor's reasoning
Precision of Claims
The argument makes a causal claim that taking LDL-C medications does not make people more likely to develop this condition, based on observational data about association patterns
Strategy
We need to identify logical flaws in how the doctor reaches the conclusion. Look for gaps between the evidence presented and the conclusion drawn. The doctor observes that people who develop this condition have lower LDL-C regardless of medication use, then concludes medications don't cause the condition. We should think about what logical errors this reasoning might contain - like confusing correlation with causation, ignoring alternative explanations, or making unwarranted assumptions about the data
This accurately identifies the core flaw in the doctor's reasoning. The doctor observes that the association between lower LDL-C and the medical condition is equally strong whether people took medications or not, then concludes that medications don't cause the condition. However, this reasoning is flawed because even if medications don't strengthen the association, they could still contribute to causing the condition by lowering LDL-C levels. The medication could be part of the causal pathway (medication → lower LDL-C → condition) without changing the strength of the observed association. This choice correctly identifies that the doctor incorrectly assumes no strengthening of association means no causal role.
This doesn't accurately describe the flaw. The doctor isn't confusing claims about medication effects with claims about condition effects. The doctor is specifically discussing medication effects throughout the argument - how medications relate to LDL-C levels and how this might relate to developing the condition. There's no confusion between medication effects and condition effects here.
This mischaracterizes the argument structure. The doctor isn't dealing with a factor that's 'not known to cause a given effect' and then making claims about other effects. The doctor is looking at medication use and its relationship to both LDL-C levels and condition development. This choice describes a different type of logical error that doesn't match what's happening in this argument.
This doesn't identify a flaw because the doctor already acknowledges that factors can be associated without one causing the other. The doctor's conclusion is actually about causation (medications don't make the condition more likely), not about association strength. The doctor doesn't overlook the possibility of association without causation - that's actually part of the doctor's reasoning.
This describes a different logical structure than what we see in the argument. The doctor isn't dealing with the presence or absence of a third factor and making claims about when associations hold. The argument is about whether medication use affects the likelihood of developing a condition, not about when associations between two other factors hold based on a third factor's presence or absence.