#25 - A recent survey showed that 50 percent of people

[Johnclem]

Hi.
With this question I see the flaw to be a sufficient and nec mix up . But what's wrong with A? - Isn't this stim also flawed for claiming more people vote based on percentages?


Thanks
-John

[Adam Tyson]

Percentages and numbers are often confused in LR stimuli, leading to flaws in the reasoning based on those mixups. That happens most often when two different groups are being compared to each other, and we don't know their relative sizes - let's say we take Group A, made up of people named John, and Group B, made up of people named Frodo, and we find that a higher percentage of the Frodos have hairy feet than the percentage of Johns that have hairy feet. We could not conclude that MORE Frodos than Johns have hairy feet, because we don't know how many Frodos and Johns there were. Maybe there was just one Frodo, and 100% (that one guy) had hairy feet, and there were 1000 Johns and 1% (10 of them) had hairy feet, so that the hairy-footed Johns outnumbered the hairy-footed Frodos 10 to 1.

In the problem you asked about, though, we don't have that problem, because we are not dealing with two different groups. Instead, we are dealing with a single group - the people surveyed. We know that a certain percentage gave one particular answer and another percentage gave a different answer, but the total number of people surveyed remains the same - no numbers and percentages problem there. To test that idea, come up with a number of people surveyed, and apply the percentages to that total and see what happens.

Good luck in your studies!

[harvoolio]

Just so I understand this correctly since both questions were asked to the same group of people a valid conclusion would have been "Therefore, more people believe that elected officials should resign if indicted than believe that they should resign only if convicted (or "that they should not resign if not convicted")."

Thanks

[James Finch]

Hi Harvoolio,

Yes, that would be a correct statement to draw. The issue in the stimulus is that the conclusion confuses the sufficient condition indicator "if" with the similar necessary condition indicator "only if."

[chiickenx]

Hi, may someone please look over my blind review? Im not quite sure if my reasoning for (A) is quite correct. Thank you!
Stimulus Summary:
Recent survey:
People polled — 50% → believe X
X: (EO → indicted for a crime) → (EO → should resign)
People polled — 35% → believe Y
Y: (EO → resign) → (EO → convicted of crime)
C. More people → believe X than Y
A.
Initially, I chose this because it went from people who were polled to people in general ... but the issue with this AC is that we do not know if the people who were polled represents the entire population or not… it could be that everyone in the population was polled. If this is the case, the conclusion still couldn't be drawn on the basis of the premises… Thus, this does not capture the flaw of the argument.
B.
Yea… The conclusion cannot be derived from the premises… In essence we have X compared with Z: ((EO → convicted)→ (EO → resign)). Our premises were about X and Y… thus, the conclusion about X and Z cannot be derived. That is the basic flaw… However, more specifically, the conclusion confused Y and Z, confusing the sufficient and necessary conditions of the two…
C.
No ambiguity of terms…
D.
The conclusion was about the two specific beliefs…?
E.
The premises are consistent....

[Jeremy Press]

Hi chiickenx,

Great work with your blind review on this question! I'm in agreement with everything you outlined in your discussion. To give you a little more color on answer choice D (about which you indicated some uncertainty), the problem is, as you note, that the conclusion is not "a conclusion about a (i.e. one) specific belief." Rather, it is a conclusion comparing the number of people who accept one specific belief to the number of people who accept another specific belief, and therefore is a conclusion about two specific beliefs.

Again, fantastic work, and keep it up!

Jeremy

[hrhyoo]

Hi Powerscore,

I got this question right but I have a bit of a problem with understanding why A is a flaw: drawing a conclusion about the population in general based on a sample selected from that population meaning the general population or the relevant population is valid unless the sample has problems including being not representative (biased or too small), asking misleading survey questions, and/or having dishonest respondents. The AC does not state any of those issues so why is it considered as either overgeneralization or survey error?

Thank you in advance,


H

[Adam Tyson]

Good questionm H! In fact, answer A as written is actually NOT a flaw! It's perfectly valid to draw conclusions about the general population based on a sample of that population. If that were not the case, then there would be no such thing as survey research or statistical analysis, and every survey would be automatically considered useless! The problems arise when the sample group is not representative of the general population about which conclusions are then drawn. If the group is too small, or lacks the appropriate diversity, for example, the sample group would then be unrepresentative, and conclusions based on that survey would not be trustworthy and the argument based on them would be flawed.

Answer A doesn't say anything about problems with the sample group, leaving open the possibility that it was large and diverse enough that we could rely on it. Using a sample group to draw conclusions about the general population is not a flaw; using an unrepresentative sample group is!

[hrhyoo]

Thanks Adam!

[ashpine17]

After reading all of the threads, I am still confused.

The flaw to me appears to be a Mistaken Reversal because the premises have: R---> C
and the conclusion reverses that: C--->R

Wouldn't that be "confusing Necessary for Sufficient" and not the other way around as it appears in (B)?