Columnist: Many car manufacturers trumpet their cars' fuel economy under normal driving conditions. For all three of ...

SamA on September 19, 2019

Hello @Julie-V,

Premise: Many car manufacturers trumpet their cars' fuel economy under normal driving conditions.

Premise: I've never reached the promised fuel economy in any of my three cars.

Conclusion: Manufacturers probably inflate their numbers.

The real problem with the argument is that the columnist is applying her experience with three cars to the car manufacturing industry as a whole. The sample size is too small. We don't even know if the columnist drives under normal conditions. Maybe she speeds or frequently takes a route with traffic jams. It does not give us enough evidence to suggest that car manufacturers inflate their numbers. This is why answer choice A is correct.

Here is the problem with answer choice C. The columnist did not overlook the possibility of bias. In fact, that seems to be her whole argument! She concludes that car manufacturers inflate their stats in order to sell cars, which sounds like bias to me.

You asked when bias can be rightfully detected. It is certainly possible that these car manufacturers are biased. But, in order to make that conclusion, we would need more information than this passage gives us. One person's experience with three cars just isn't enough.