To evaluate overall tap water safety across a metropolitan region containing over 100,000 residential units, a municipal environmental agency tested water samples collected exclusively from 500 newly constructed apartment complexes built within the last two years. Finding no detectable levels of lead or industrial contaminants in any of the tested samples, the agency concluded that the region's entire residential tap water infrastructure is free from lead contamination.
The reasoning in the agency's argument is most vulnerable to criticism on the grounds that it
- draws a definitive conclusion about the entire residential water system based on a sample of buildings that, owing to their recent construction, may not be representative of older structures.Answer
- Bfails to establish that tap water safety is a primary concern for residents currently occupying newly built apartment complexes.
- Cassumes that lead is the only harmful industrial contaminant capable of affecting municipal water supplies.
- Doverlooks the potential side effects of upgrading water treatment plants in neighboring municipalities.
- Econfuses the absolute number of tested water samples with the percentage of total residential units built within the last two years.
Answer
The argument is vulnerable because it draws a conclusion about all residential buildings based on a sample of newly constructed complexes, which are likely subject to modern lead-free building codes and thus unrepresentative of older housing stock.
The correct answer highlights a classic sampling bias: testing only recently built properties creates a selection bias because modern plumbing standards typically prohibit lead materials. Concluding that all 100,000+ residential units are lead-free based on a sample that excludes older, higher-risk structures is a flawed generalization.
Step-by-Step Solution
Key Concept
Sampling and Generalization Flaws (Unrepresentative Sample Bias)
Estimated Time:2m 0s