#13 - If retail stores experience a decrease in revenues

[ameliashaffer]

I understand why it is C, but I am confused why we rule D out. I connected the conditional statements as follows:

DR = decreased revenue, AC = attitudes changed, PR = prices risen, SKP = salaries kept pace

DR --> AC or PR
AC Not and PR Not --> DR Not
PR --> SKP Not
SKP --> PR Not

Given the question stem, I combined the chains to be "SKP --> PR Not and AC Not --> DR Not"

Are you not allowed to combine the "SKP --> PR Not" with the "PR Not AC Not ==> DR Not." Doing so gave me Answer D.

Thanks!

[Dana D]

Hey Amelia,

Be careful here - the stimulus says (and you correctly diagrammed) that if there is a decreased revenue, attitudes have changed OR prices have risen.

DR Attitudes changed OR prices have risen

Your error was when you combined the conditional logic as "SKP --> PR Not and AC Not --> DR Not". In MBT questions, the correct answer choice would be one that we can infer from the stimulus alone. However, just based on the stimulus and the additional information of "salaries have kept pace with rising prices", we cannot definitively say that attitudes have not changed. It's possible that they have changed, which would mean stores could still experience a decrease in revenue.

Does that make sense?

[floydbtric@gmail.com]

Hey all,

I don't understand why D is not the correct choice. As by my diagrams which seem to align with everyone else's, it looks to me like it satisfies all the needs.

DR - decreased revenue
Attchange - attitude change
PR - price rise
skp - salaries keep pace

-> Attchange -----> celebrate
DR ------| OR
-> pr ----------------> NO skp


Contrapositives:

(skp----> NO pr)
AND | together ------------------> NO DR
(NO celebrate ------> NO attchange)

The stimulus provides skp (bold):

(skp----> NO pr)
AND | together ------------------> NO DR
(NO celebrate ------> NO attchange)

And D as an answer choice provides:

(skp----> NO pr)
AND | together ------------------> NO DR
(NO celebrate ------> NO attchange)

[Jeff Wren]

Hi floyd,

First, if you haven't done so already, I'd recommend reading the prior explanations on this forum post, as many students had questions about Answer D.

To address your question, I think that you are confusing conditional statements (in the stimulus) with non-conditional statements of fact (in Answer D).

The stimulus tells us that:

If retail stores have a decrease in revenue, then either attitudes towards gifts has changed or prices have risen beyond what people can afford.

This can be diagrammed:

RSDR -> ATGC or PRBPA

(For simplicity, I'm going to hold off on the other conditional statements for now.)

Now if we learn that one of these necessary terms doesn't happen, such as "prices have NOT risen beyond what people can afford" (Not PRBPA), this doesn't tells us anything about RSDR or ATGC. It's possible that retail stores have a decrease in revenue (in which case we'd also know that attitudes towards gifts must have changed), but it's also possible that retail stores did NOT have a decrease in revenue.

We are able to infer that "prices have NOT risen beyond what people can afford" (Not PRBPA) based on the fact that salaries have kept pace with prices using the contrapositive of the third conditional statement in the stimulus, which is why Answer C is correct.

However, as stated above, knowing that one of the possible necessary conditions didn't happen does tells us anything about the original sufficient condition or the other necessary condition.

Answer D is not conditional. It is NOT saying "If attitudes towards gifts have Not changed, then retail stores will Not have a decrease in revenue." Instead it is stating definitely that the other necessary condition did Not happen and the sufficient condition did Not happen, and we have no proof of this at all.

Here's a (hopefully) easier to follow example.

If I went to Hawaii, then I either went surfing or I went scuba diving.

I then tell you that I did not go scuba diving.

Answer D would be saying "I did not go surfing and I did not go to Hawaii." This, of course, is not proven by the fact that I did not go scuba diving.

[Dancingbambarina]

Hi,

Would I be correct in assuming it can't be B because BOTH primary necessary conditions would have to NOT be met to trigger the contrapositive of reduced prices. You have made the chains seperate, but I do not see why. It makes sense having a common "Reduced Prices" and then two, bi-conditional chains.

[Amber Thomas]

Hi Dancingbambarina!

These are our relationships:

DR = Retail Stores Experience a Decrease in Revenue
AC = Attitudes Changed Towards Extravagant Gift-Giving
PR = Prices Have Risen
C = Something to Celebrate
SNKP = Salaries Have Not Kept Pace with Rising Prices

DR --> AC or PR; ~AC and ~PR --> ~DR

AC --> C; ~C --> ~AC

PR --> SNKP; ~SNKP --> ~PR

You're absolutely right. Answer Choice B means ~DR, so for this to be true, we would need both ~AC and ~PR be true. However, the question stem only asserts that ~SNKP, so the only thing we can guarantee to be true is ~PR. That only gives us half of the equation to conclude that ~DR (which is what is asserted in Answer Choice B).

I hope this helps!

[Dancingbambarina]

Hi Dancingbambarina!

These are our relationships:

DR = Retail Stores Experience a Decrease in Revenue
AC = Attitudes Changed Towards Extravagant Gift-Giving
PR = Prices Have Risen
C = Something to Celebrate
SNKP = Salaries Have Not Kept Pace with Rising Prices

DR --> AC or PR; ~AC and ~PR --> ~DR

AC --> C; ~C --> ~AC

PR --> SNKP; ~SNKP --> ~PR

You're absolutely right. Answer Choice B means ~DR, so for this to be true, we would need both ~AC and ~PR be true. However, the question stem only asserts that ~SNKP, so the only thing we can guarantee to be true is ~PR. That only gives us half of the equation to conclude that ~DR (which is what is asserted in Answer Choice B).

I hope this helps!

Thank you so much Amber!

[Dancingbambarina]

Your analysis was perfect right up to where you realized you went wrong, gavelgirl. The problem is that there is no conditional relationship between "attitudes change" and "prices rise." If there is a decrease in revenue, then we know that at least one of those two necessary conditions must happen, but one of them failing to happen tells us nothing about the other one because we don't know if there has been a decrease in revenue! Your first prephrase was your best prephrase, that prices have not risen beyond what most people can afford, and that's what you should have been looking for in the answers. Don't over-complicate it! The only way we could know that attitudes had changed would be if we knew that prices had not risen AND that revenues had decreased.

Put another way, in a multi-conditional relationship (two conditions connected by "and" or "or") the failure of, or occurrence of, one necessary condition tells you nothing about the other necessary condition. If there is no arrow that connects them to each other, don't go there!

Pertaining to the conditional "Either... Or", surely the construct keeps its nature of "if this doesn't happen, then the other must happen" ?

I ask because it makes sense when OR is in the necessary with this original construction, but when in the sufficient, would knowing one didn't happen mean the other MUST happen, even if we don't know it happens and furthermore don't even know it leads to the necessary condition?



Thank you

[Dancingbambarina]

Your analysis was perfect right up to where you realized you went wrong, gavelgirl. The problem is that there is no conditional relationship between "attitudes change" and "prices rise." If there is a decrease in revenue, then we know that at least one of those two necessary conditions must happen, but one of them failing to happen tells us nothing about the other one because we don't know if there has been a decrease in revenue! Your first prephrase was your best prephrase, that prices have not risen beyond what most people can afford, and that's what you should have been looking for in the answers. Don't over-complicate it! The only way we could know that attitudes had changed would be if we knew that prices had not risen AND that revenues had decreased.

Put another way, in a multi-conditional relationship (two conditions connected by "and" or "or") the failure of, or occurrence of, one necessary condition tells you nothing about the other necessary condition. If there is no arrow that connects them to each other, don't go there!

Pertaining to the conditional "Either... Or", surely the construct keeps its nature of "if this doesn't happen, then the other must happen" ?

I ask because it makes sense when OR is in the necessary with this original construction, but when in the sufficient, would knowing one didn't happen mean the other MUST happen, even if we don't know it happens and furthermore don't even know it leads to the necessary condition?



Thank you

My apologies, I think I understand. It's similar to the "Neither...Nor" example earlier in the thread. If Either Or is by itself, then NotA --> B suffices. If it's connected to a necessary, then means either Not A or B can be the suffiecient condition. It's a bit confusing but I am slowly getting it.

Thanks