# Question about the diagnostic example



## Chunhui Jiang (Mar 29, 2016)

I plan to take the PE exam this year, and I found a diagnostic example from NCEES.

Attached is the graph, and I have a question about it. We could see the distance between the average of passing and what the person did, but the distance refers to the distance of *correct percentage* or *number of correct answer*?

For example, we could measure (by ruler) that the distance (length of orange part) for Mass Balances is about *1.5 times* of the distance (length of orange part) for Energy Balances &amp; Thermodynamics, but is the "1.5" refers to the ratio of " number for correct answer of average passing for Mass Balances minus 3" to "number for correct answer of average passing for Energy Balances &amp; Thermodynamics minus 5"?

Or the number of "1.5" refers to the ratio of " percentage for correct answer of average passing for Mass Balances minus 33%" to "percentage for correct answer of average passing for Energy Balances &amp; Thermodynamics minus 50%"?

If someone can help me with this question, and provide me the answer, I will be able to calculate the percentage score for passing the whole exam based on this graph.

Thanks.


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## P-E (Mar 29, 2016)

seriously, don't worry about the passing score.  Study like you need to get all of them correct.  If you must, just assume 70%.


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## Chunhui Jiang (Mar 30, 2016)

P-E said:


> seriously, don't worry about the passing score.  Study like you need to get all of them correct.  If you must, just assume 70%.


Thanks for your reply.

I agree with you, but I am interested in solving this problem by mathematics as an engineer, so I want to calculate for an accurate answer.


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## P-E (Mar 30, 2016)

Chunhui Jiang said:


> Thanks for your reply.
> 
> I agree with you, but I am interested in solving this problem by mathematics as an engineer, so I want to calculate for an accurate answer.


Unfortunately, the passing score changes from year to year and by discipline.  They will never tell you.


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## Chunhui Jiang (Mar 30, 2016)

P-E said:


> Unfortunately, the passing score changes from year to year and by discipline.  They will never tell you.


Yes, but my goal is calculating for an accurate data based on this graph even this graph cannot prove other conditions.


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## knight1fox3 (Mar 30, 2016)

Chunhui Jiang said:


> Yes, but my goal is calculating for an accurate data based on this graph even this graph cannot prove other conditions.


You are welcome to interpret the graph as you see fit to make your perceived calculations.  However, based on your first post, the questions you have can only be made using certain _*assumptions*_ since NCEES controls the true calculation process.  So based on that, your calculations will be at best theoretical.  Seems like an exercise in futility as I'd rather be spending my time more wisely preparing for the exam itself.


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## JHW 3d (Mar 30, 2016)

I don't think the bars refer to a strict ratio OR absolute value. They are almost artistic.

For example in no case will getting ZERO correct NOT result in you getting a full length bar to the left (even for topics where there is only one problem!). In no case did getting EVERY problem correct result in getting a full length bar to the right. Definitely not scaled, and definitely not absolute offset.

Only thing I can think of is that NCEES doesn't want you to feel good about getting a topic completely correct and hence doesn't publish a result that says YOU CRUSHED fluid transport --"don't worry about it next time!!"


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## Chunhui Jiang (Mar 31, 2016)

knight1fox3 said:


> You are welcome to interpret the graph as you see fit to make your perceived calculations.  However, based on your first post, the questions you have can only be made using certain _*assumptions*_ since NCEES controls the true calculation process.  So based on that, your calculations will be at best theoretical.  Seems like an exercise in futility as I'd rather be spending my time more wisely preparing for the exam itself.


Yes, and I think you are right, but I will still try.


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## Chunhui Jiang (Mar 31, 2016)

JHW 3d said:


> I don't think the bars refer to a strict ratio OR absolute value. They are almost artistic.
> 
> For example in no case will getting ZERO correct NOT result in you getting a full length bar to the left (even for topics where there is only one problem!). In no case did getting EVERY problem correct result in getting a full length bar to the right. Definitely not scaled, and definitely not absolute offset.
> 
> Only thing I can think of is that NCEES doesn't want you to feel good about getting a topic completely correct and hence doesn't publish a result that says YOU CRUSHED fluid transport --"don't worry about it next time!!"


I think I found something.

We could find out that this examinee did all two questions wrong in term 12, and did all two questions correct in term 18, but the length of the two bars are not the same, which could prove that the graph shows the scale, and the reason is the average is more than 1 question or 50%.

From term1 and term 10, we could find that the graph is based on the percentage, but not number.

The only thing is that for term 8,10,12,20, the real bar may be longer than the bar shown on the graph, because the distance of percentage is too big to show, and has covered all the length to the left, so these data maybe not accurate, but I think other terms shows the scale.

Thanks.


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## Audi Driver P.E. (Mar 31, 2016)

I'm having a hard time thinking of an exercise that is more frivolous or futile.  Take, for example, the simple fact that a 50% in one case results in a bar to the right, and in another, results in a bar to the left.  These graphs don't mean what you think you mean. I don't think they even mean what the NCEES thinks they mean.


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## snickerd3 (Mar 31, 2016)

Audi driver said:


> I'm having a hard time thinking of an exercise that is more frivolous or futile.  Take, for example, the simple fact that a 50% in one case results in a bar to the right, and in another, results in a bar to the left.  These graphs don't mean what you think you mean. I don't think they even mean what the NCEES thinks they mean.


I think the switch to this format from previous is the biggest DISSERVICE NCEES has ever done for test takers.


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## Chunhui Jiang (Mar 31, 2016)

Audi driver said:


> I'm having a hard time thinking of an exercise that is more frivolous or futile.  Take, for example, the simple fact that a 50% in one case results in a bar to the right, and in another, results in a bar to the left.  These graphs don't mean what you think you mean. I don't think they even mean what the NCEES thinks they mean.


The reason is that for some term of the questions, the average collect percentage is less than 50%, but for some term, that is larger than 50%.


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## Chunhui Jiang (Mar 31, 2016)

snickerd3 said:


> I think the switch to this format from previous is the biggest DISSERVICE NCEES has ever done for test takers.


I think NCEES really do not want us to know the passing score.


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## thekzieg (Mar 31, 2016)

Chunhui Jiang said:


> I think NCEES really do not want us to know the passing score.


Exactly.


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## Audi Driver P.E. (Mar 31, 2016)

Chunhui Jiang said:


> The reason is that for some term of the questions, the average collect percentage is less than 50%, but for some term, that is larger than 50%.


So you think.  You don't know anything for sure, it's all purely guessing.  Thus: futile.


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## snickerd3 (Mar 31, 2016)

Chunhui Jiang said:


> I think NCEES really do not want us to know the passing score.


that has always been obvious.  I am talking about the format of the diagnostic report in general.  Previously it just identified where the person needed to work harder.  now they provide the bars and it leads to all this unnecessary guesswork calculations on what the minimum needed to pass next time vs trying to actually study and try to try to score higher.


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## Chunhui Jiang (Mar 31, 2016)

thekzieg PE said:


> Exactly.


But we can calculate for that.


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## Chunhui Jiang (Mar 31, 2016)

Audi driver said:


> So you think.  You don't know anything for sure, it's all purely guessing.  Thus: futile.


Of course I am sure about the answer of your question.


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## Chunhui Jiang (Mar 31, 2016)

snickerd3 said:


> that has always been obvious.  I am talking about the format of the diagnostic report in general.  Previously it just identified where the person needed to work harder.  now they provide the bars and it leads to all this unnecessary guesswork calculations on what the minimum needed to pass next time vs trying to actually study and try to try to score higher.


I do not know about others, but for me, I am just curious and want to do a calculation, and I do not think it will have any effect on my study.


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## Audi Driver P.E. (Mar 31, 2016)

Chunhui Jiang said:


> Of course I am sure about the answer of your question.


hahahahahaha I don't even have a question.


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## Chunhui Jiang (Mar 31, 2016)

Audi driver said:


> hahahahahaha I don't even have a question.


Well, I just gave the explanation of " the simple fact that a 50% in one case results in a bar to the right, and in another, results in a bar to the left".


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## Audi Driver P.E. (Mar 31, 2016)

Chunhui Jiang said:


> Well, I just gave the explanation of " the simple fact that a 50% in one case results in a bar to the right, and in another, results in a bar to the left".


Which, of course, is not a question, and your explanation isn't even necessarily correct.  Give it a rest.


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## thekzieg (Mar 31, 2016)

You really can't calculate it though. Because NCEES reserves the right to adjust the passing score based on whatever they want. They can throw questions out if they want. They can decide too many people are getting a section right, and make the cut score higher. The diagnostic is also comparing you _to other people taking the exam. _If you're taking the same exam as a bunch of unprepared people the cut score will change. And I'm also not convinced that the cut score is the same for every _version_ of the exam, even within the same breadth/depth.

If, however, you're still convinced that calculating this is possible and reasonable, try the calc once with the bars representing percentages and once with the bars representing ratios, and see what you get. Your calculation will be equally helpful either way.


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## Chunhui Jiang (Mar 31, 2016)

Audi driver said:


> Which, of course, is not a question, and your explanation isn't even necessarily correct.  Give it a rest.


It is just a qualitative analysis.


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## Chunhui Jiang (Mar 31, 2016)

thekzieg PE said:


> You really can't calculate it though. Because NCEES reserves the right to adjust the passing score based on whatever they want. They can throw questions out if they want. They can decide too many people are getting a section right, and make the cut score higher. The diagnostic is also comparing you _to other people taking the exam. _If you're taking the same exam as a bunch of unprepared people the cut score will change. And I'm also not convinced that the cut score is the same for every _version_ of the exam, even within the same breadth/depth.
> 
> If, however, you're still convinced that calculating this is possible and reasonable, try the calc once with the bars representing percentages and once with the bars representing ratios, and see what you get. Your calculation will be equally helpful either way.


I agree, and I  am just curious and want to do a calculation, and I do not think it will have any effect on my study.


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## Audi Driver P.E. (Mar 31, 2016)

Chunhui Jiang said:


> It is just a qualitative analysis.


Whatever you want to believe, I guess.  Obviously a group of us can't dissuade you from your fairy tale, so just go with it.  Good luck on your exam, it sounds like you're going to need it.


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## Chunhui Jiang (Mar 31, 2016)

Audi driver said:


> Whatever you want to believe, I guess.  Obviously a group of us can't dissuade you from your fairy tale, so just go with it.  Good luck on your exam, it sounds like you're going to need it.


Thanks, and wish you good


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## JHW 3d (Mar 31, 2016)

Best case scenario you determine what cut score was in the exam you took and failed. It has no bearing on any subsequent exams.

On second thought I think you don't really care and are just looking for some kind of intellectual pursuit. But, why involve the rest of us in this sadistic nightmare?


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## Chunhui Jiang (Mar 31, 2016)

JHW 3d said:


> Best case scenario you determine what cut score was in the exam you took and failed. It has no bearing on any subsequent exams.
> 
> On second thought I think you don't really care and are just looking for some kind of intellectual pursuit. But, why involve the rest of us in this sadistic nightmare?


Haha,

I am just curious about it, and I am sorry for involving you in this nightmare. I did not do it in purpose.


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## Mike in Gastonia (Mar 31, 2016)

thekzieg PE said:


> You really can't calculate it though. Because NCEES reserves the right to adjust the passing score based on whatever they want. They can throw questions out if they want. They can decide too many people are getting a section right, and make the cut score higher. The diagnostic is also comparing you _to other people taking the exam. _If you're taking the same exam as a bunch of unprepared people the cut score will change. And I'm also not convinced that the cut score is the same for every _version_ of the exam, even within the same breadth/depth.
> 
> If, however, you're still convinced that calculating this is possible and reasonable, try the calc once with the bars representing percentages and once with the bars representing ratios, and see what you get. Your calculation will be equally helpful either way.


PE magazine had a pretty good article about how the exams are developed. It also had a section about exam myths that cover a lot of your ideas.

http://www.nspe.org/resources/pe-magazine/march-2016/the-ultimate-test


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## Chunhui Jiang (Mar 31, 2016)

Mike in Gastonia said:


> PE magazine had a pretty good article about how the exams are developed. It also had a section about exam myths that cover a lot of your ideas.
> 
> http://www.nspe.org/resources/pe-magazine/march-2016/the-ultimate-test


I will also read it, thanks.


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## TWJ PE (Apr 3, 2016)

Mike in Gastonia said:


> PE magazine had a pretty good article about how the exams are developed. It also had a section about exam myths that cover a lot of your ideas.
> 
> http://www.nspe.org/resources/pe-magazine/march-2016/the-ultimate-test


Good read. Thank you.


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