PT 54 LR Section 4 #20

KylieMorrison
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PT 54 LR Section 4 #20

Postby KylieMorrison » Sun Sep 26, 2010 12:05 am

I may be over thinking this question and answer but I'm still confused as to how A would strengthen the argument.
The conclusion is that the meteorologist claims his station's weather forecasts are more useful and reliable than those of the most popular news station in the area because on most of the ocasions when he has forecast rain for the next day, it has rained and the same cannot be said for the competitors.

A says the meteorologist stations forecast rain more often than did the most popular news station in the area. But how does this "most strengthen" the argument? I would think, the meteorologists staion would have forecast less rain than the competition to strengthen the argument. Lets says the meteorologist forecast rain for the next day 100 days out of the year, was right 90 of those days and the most popular news station forecast rain for the next day 200 days out of the year and was right 90 of those days. The metorologist has a 90% accuracy rate while the competitor had a 45% accuracy rate. That would support the conclusion that they are more useful and reliable.

If someone could please let me know why A is the best answer I would really appreciate it! Also it would really help me if you use numbers to show how A could strengthen, I am a visual person so I will understand more quickly that way. Thanks!

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Jack Smirks
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Re: PT 54 LR Section 4 #20

Postby Jack Smirks » Sun Sep 26, 2010 12:43 am

Ok so the meteorologist claims that his station forecasts are more reliable than the most popular news station in terms of reliability. He claims that on "most" occasions when they have forecasted rain the next day, they have been correct. Remember "most" on the LSAT means more than half.

He also adds that the same cannot be said for the stations competitors. This means that the competitors have not been accurate in "most" of their predictions and therefore, are only correct in half of their predictions or less than half of their predictions.
So from this we know that the only possible scenario in which the competitors are more reliable, is one in which the competitors TOTAL number of forecasts correct are greater than the TOTAL number of the meteorologists forecasts that are correct.
Think of it this way:

MS= Meteorologist's Station CS= Competitors Station

MS: 6 days correct out of 10 forecasts = 60% (more than half) accuracy and 6 days total

(Remember: The competitors station has to be equal to or less than 50% in terms of their forecasts accuracy)
So the only way for the competitors station to have been more reliable in their forecasts is to have been correct a GREATER TOTAL NUMBER OF DAYS.

CS: 7 days correct out of 14 forecasts = 50% (exactly half) accuracy and 7 DAYS TOTAL (making them more accurate than MS in regard to the TOTAL number of days forecasted correctly)

Answer choice A, says that MS did in fact forecast more days than did CS and eliminates the possibility of the CS being correct on their forecast on a TOTAL NUMBER OF DAYS in comparison to the MS.

A. therefore strengthens the argument.

JD2014
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Re: PT 54 LR Section 4 #20

Postby JD2014 » Sun Sep 26, 2010 1:02 am

As the question stem states, "the most important question for viewers in this area is whether it will rain, and on most of the occasions when we have forecast rain for the next day, we have been right."

If the meteorologist's station has forecast rain more often than the most popular station, and they are right on most occasions, that would mean there are a number of instances where the most popular station has failed to predict rain, and people left home without umbrellas and got wet, while the meteorologists station correctly forecast rain and its viewers were prepared. As this is the most important issue for viewers, it strengthens the argument that the meteorologists forecasts are more useful and reliable.

To use numbers, if it rained 100 times in the year, and assume they had an 85% accuracy rate, they called 85 of those days and, since they are right "most of the occasions when [they] forecast rain," they could have had no more than 169 predictions. (Over 50% accuracy.) In contrast, if the popular station only predicted rain 120 times, and their accuracy is below 50% ("the same cannot be said for either of our competitors [that they are right most of the time]"), then they could have predicted no more than 59 of the rainy days. It's 59/100 vs. 85/100. Your calculation assumes the popular news station could have been more accurate, which is negated in the question stem.

The calculation is even simpler if you don't include false positives and rates. If it rained 100 times in the year, the meteorologist correctly predicted 85 of them and the popular station correctly predicted 70 of them.

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suspicious android
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Re: PT 54 LR Section 4 #20

Postby suspicious android » Sun Sep 26, 2010 2:41 am

I could probably forecast rain correctly 99% of the time as long as I waited until there was thunder and lightning and the barometer drops a few points. I wouldn't even need any instruments. I'd probably only end up forecasting rain maybe 5-10 times a year, even though it might rain in my city 40 times a year. That wouldn't be very helpful, though. The weatherman's telling us that's not his style. He's accurate and he forecasts rain more often than the competitors, so he's not wussing out by just forecasting rain during the middle of a thunderstorm.

MissLucky
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Re: PT 54 LR Section 4 #20

Postby MissLucky » Mon Oct 04, 2010 4:11 pm

JD2014 wrote:If the meteorologist's station has forecast rain more often than the most popular station, and they are right on most occasions, that would mean there are a number of instances where the most popular station has failed to predict rain, and people left home without umbrellas and got wet, while the meteorologists station correctly forecast rain and its viewers were prepared. As this is the most important issue for viewers, it strengthens the argument that the meteorologists forecasts are more useful and reliable.


Not necessarily. According to (A), the meteorologist's station forecasts rain more often (maybe 10 more times) than the most popular news station, but those 10 times could turn out to be precisely those minority occasions on which the meteorologist's station has forecast rain for the next day and it was NOT correct!!

but then at that point, I guess the meteorologist's station has only accurate forecasts left, and the most popular news station in the area still has less than most of its forecasts for the rain the next day being correct? this quest. is getting me confused.

I get suspicious android's point though and I guess in that way it's clear that at the very least (A) is eliminating the objection that "hey! the meteorologist's station just forecasts rain those few times a year when it's blatantly obvious to anyone, whereas the popular news station forecasts rain those times and additional times when it is not so obvious and that's why it has a poorer record but is still more useful and reliable"




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