Logical Reasoning

PT142 · S2 · Q20 When people show signs

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When people show signs of having a heart attack an electrocardiograph (EKG) is often used to diagnose their condition.

Conclusion

Interpreting EKG data should be left to computer programs.

Evidence

In a study, a computer program went up against a skilled cardiologist, and of the cases that were later confirmed to be heart attacks, the computer guessed "heart attack" more than the the cardiologist did.

Evaluation

There are two very different attack lines to consider here: A) I do not accept that the EKG won this study B) I accept that the EKG won, but we still shouldn't leave interpreting EKG to computers

A) When it comes to diagnosing an EKG for whether someone had a heart attack, you can be wrong in two different ways: false positives (you said "heart attack" but it wasn't) or false negatives (you said "no heart attack" but it was). We only know that the computer won the false negative battle. The doctor was more often guilty of a false negative, where she said it wasn't a heart attack but later it was confirmed that it was. But it could be that the computer was way worse at false positives. Maybe the computer almost always said "heart attack", so of course it nailed all the cases of genuine heart attacks but made tons of mistakes when the case was not actually a heart attack.

LSAT has rolled out this type of argument multiple times -- (45-1-24 about DNA tests and 54-4-20 about forecasting rain)

B) Even if the computer were more accurate in diagnosing EKG's, there could be other factors that would argue against making computers the exclusive diagnostic device for EKG data (cost, availability, bedside manner, patient perception, etc.)

Goal

Look for an answer that suggests that the EKG didn't necessarily win the study's contest (because it may have generated tons of false negatives), or look for a consideration beyond accuracy that would make it seem like we should use humans, not exclusively computers, to diagnose EKG.

20.

Which one of the following, if true, most weakens the argument?

  1. Experts agreed that the cardiologist

    Opposite

    This seems to mildly strengthen. Someone might have argued, "Wait a sec -- don't turn over EKG data to computers just yet. This cardiologist they used in the study wasn't as good as a normal cardiologist would've been, despite being very experienced + highly skilled." This answer would wipe away that objection, saying, "No, she was good. Other experts verified that she made few, if any, obvious errors."

    1% picked this

  2. The practice of medicine is

    Weak Impact

    Because this gets so broad ("the practice of medicine") when our topic is quite narrow ("interpreting EKG data"), it's hard to use this idea as any focused attack on the argument. The author could say, "Yes, of course medicine is both art and science. I'm not saying a computer should replace all human medical doctors. I'm only saying a computer might be better at crunching EKG data." If this answer said "the practice of interpreting an EKG" involves a lot of subjective or intuitive judgments that are hard for computers, then it would have more impact.

    7% picked this

  3. Correct

    The cardiologist correctly diagnosed a

    Why this is right

    This answer says that the doctor won when it came to false negatives. If we went with the computer's diagnosis, then a lot of people who didn't have heart attack would be told that they did. If we went with the cardiologist's, then a lot of people who did have a heart attack would be told that they didn't. Neither situation is great. This answer isn't picking one over the other; it's just saying, "Whoa, there. The computer by no means won the competition against the cardiologist. Seems like more of a tie."

    Skill tested: Weaken · how this choice captures the argument's function is the move to repeat next time.

    71% picked this

  4. In a considerable percentage of

    No Impact

    This argument is only about who's going to interpret the EKG data: a computer or a cardiologist. This answer is about cases in which neither one could make an accurate judgment, so it doesn't make us lean one way or the other.

    10% picked this

  5. The cardiologist in the study

    Opposite

    Those wily rascals. Normally pointing out an unrepresentative sample weakens an argument, but in this case the fact that the cardiologist was unrepresentative helps the argument: she's unlike most cardiologists in that she is VERY experienced and HIGHLY skilled. (granted, there could be other ways in which she's unrepresentative, but we already know she's a positive outlier when it comes to experience and skill, so we don't need to go speculating about other ones) If I was trying to convince you that I had built an amazingly powerful chess computer, would you be more impressed if the computer beat someone who was representative of people in general who play chess, or more impressed if the computer beat one of the top 10 players in the world?

    10% picked this

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