Examkin

Question

Difficulty: MediumCausal Flaws and Confounding Variables

An agronomist conducted a study of wheat farms across an agricultural county and observed that farms using a specialized microbial soil supplement achieved significantly higher crop yields per acre than farms that did not use the supplement. Based on this observation, the agronomist concluded that applying the microbial supplement directly causes an increase in wheat yields.

Which of the following, if true, most seriously weakens the agronomist's argument?

  1. The farms that chose to adopt the microbial supplement were also those that utilized advanced drip-irrigation and targeted nutrient management systems.Answer
  2. B
    Soil samples from fields treated with the microbial supplement showed a rapid increase in beneficial bacterial populations within two weeks of application.
  3. C
    Wheat produced on farms using sustainable agricultural practices commands a higher market price per bushel than conventionally grown wheat.
  4. D
    Synthetic chemical fertilizers have been shown to increase crop yields in corn and soybean cultivation in neighboring counties.
  5. E
    The retail purchase price of the microbial soil supplement increased significantly during the final year of the agronomist's study.

Answer

The argument is most seriously weakened by the choice stating that farms adopting the microbial supplement also utilized advanced drip-irrigation and targeted nutrient management systems.
The conclusion asserts a direct causal link between the microbial supplement and increased wheat yield. The correct choice reveals that the farms using the supplement were self-selected operations that simultaneously employed advanced irrigation and nutrient systems. These additional practices represent confounding variables that could fully account for the higher crop yields, severely undercutting the agronomist's conclusion.

Step-by-Step Solution

1
Identify the premise and conclusion of the causal argument
Premise: Farms using a microbial supplement had higher wheat yields per acre than farms not using it. Conclusion: The microbial supplement directly causes higher wheat yields.
Understanding the precise gap between observed correlation and claimed causation is essential for evaluating critical reasoning items.
2
Evaluate the logical vulnerability
The argument assumes that no third factor (confounding variable) accounts for the difference in crop yields between the two groups of farms.
Causal conclusions drawn from observational studies are vulnerable to selection bias and confounding variables.
3
Identify the option that introduces a confounding factor
The option pointing out that supplement-using farms also implemented advanced drip-irrigation and targeted nutrient systems establishes an alternative explanation for the increased yield.
If another major yield-enhancing factor was systematically present on the same farms, the observed increase in yield cannot be reliably attributed to the microbial supplement.

Key Concept

Causal Flaws and Confounding Variables
Estimated Time:1m 30s
Rate this question

Topics

Causal Flaws and Confounding Variables

More questions from this topic