Does the following make sense to you:

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Discussion Overview

The discussion revolves around the concept of expressing reductions as percentages of a total amount. Participants explore the clarity and implications of such expressions in mathematical contexts, including potential misunderstandings and the effectiveness of communication in mathematical language.

Discussion Character

  • Exploratory
  • Debate/contested
  • Conceptual clarification
  • Mathematical reasoning

Main Points Raised

  • Some participants affirm that expressing a reduction as a percentage of the total amount makes sense, citing examples with numerical values.
  • Others argue that the phrasing can lead to confusion, particularly regarding whether the reduction refers to the original total or the remaining items.
  • Concerns are raised about the clarity of language in mathematical statements, with references to common pitfalls in wording that can lead to misinterpretation.
  • Some participants mention the concept of percentage points (pp) as an alternative way to express reductions, although this is also questioned in terms of clarity.
  • There is a discussion about the implications of using percentages multiple times in calculations, emphasizing the need for careful treatment of such expressions.
  • Several participants express uncertainty about the term "reduction percentage" and its meaning, indicating a lack of consensus on terminology.
  • Some participants reflect on the broader implications of how percentages are presented in everyday contexts, suggesting that many people may not fully understand them.

Areas of Agreement / Disagreement

Participants do not reach a consensus on the clarity and effectiveness of expressing reductions as percentages. While some find it understandable, others highlight significant ambiguities and potential for misunderstanding.

Contextual Notes

Limitations include varying interpretations of what constitutes a reduction and the potential for confusion when percentages are used in multiple contexts. The discussion also highlights the importance of precise language in mathematical communication.

Who May Find This Useful

This discussion may be of interest to individuals engaged in mathematical communication, educators, and those exploring the nuances of percentage calculations in various contexts.

NotAnEngineer
"expressing a reduction, as a percentage of the total amount"

I.e...

If I have 20 of 100 items then I have 20%.

If I reduce that number to 15 then I would have 15%.

That would be a reduction of 5 items, or a 25% reduction%.OR

a reduction of 5% of the total amountEDIT: this is not a trick, or some mind game. just take the original phrase at face value. If someone said to you "Im going to express the reduction/addition, as a percentage of the total amount" does that make sense to you??

Im just trying to get a general feel that if I express something like that, would the average "math" person pick up on what I said?
 
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yes , yes it does make sense
 
NotAnEngineer said:
"expressing a reduction, as a percentage of the total amount"

I.e...

If I have 20 of 100 items then I have 20%.

If I reduce that number to 15 then I would have 15%.

That would be a reduction of 5 items, or a 25% reduction%.


OR

a reduction of 5% of the total amount

OR

a reduction by 5pp (percentage point)

http://en.wikipedia.org/wiki/Percentage_point
 
NotAnEngineer said:
"expressing a reduction, as a percentage of the total amount"

I.e...

If I have 20 of 100 items then I have 20%.

If I reduce that number to 15 then I would have 15%.

That would be a reduction of 5 items, or a 25% reduction%.OR

a reduction of 5% of the total amount

Here is where statements can get one into trouble if not expressed fully in some understandable manner. This reminds me of math problems that come out wrong due to language and are used as lessons. I recall some tricky wording with a hotel and rates.
Imo this is horribly worded. I often catch myself doing the same thing.

My first problem:

If I reduce that number to 15... Are you now only choosing 15 out of the original 100? Or have you actually taken out removed 5 items of the original 20 so that we now have 15 out of 95?
 
pgardn said:
Here is where statements can get one into trouble if not expressed fully in some understandable manner. This reminds me of math problems that come out wrong due to language and are used as lessons. I recall some tricky wording with a hotel and rates.
Imo this is horribly worded. I often catch myself doing the same thing.

My first problem:

If I reduce that number to 15... Are you now only choosing 15 out of the original 100? Or have you actually taken out removed 5 items of the original 20 so that we now have 15 out of 95?

How would you word it??
 
NotAnEngineer said:
"expressing a reduction, as a percentage of the total amount"

I.e...

If I have 20 of 100 items then I have 20%.

If I reduce that number to 15 then I would have 15%.

That would be a reduction of 5 items, or a 25% reduction%.


OR

a reduction of 5% of the total amount

That statement doesn't make it clear what is meant without adding the rest of the story. It is a 'bad' use of the maths. It's true that the 5 items represent 5% of the original 100 and it's true that 5 items represent 25% of the 20 - but so what? The statement is not actually wrong but what sense is there in making it?
Percentages, used more than once in an argument need to be treated with care because people often try to pull a fast one that way.

Multiple 'percentage' reductions should be dealt with correctly, that is by multiplication.
Thus, 20% off then another 10% off is 0.8 X 0.9 (=0.72) or 72%, which means 28% overall reduction and not 30%.
 
sophiecentaur said:
That statement doesn't make it clear what is meant without adding the rest of the story. It is a 'bad' use of the maths. It's true that the 5 items represent 5% of the original 100 and it's true that 5 items represent 25% of the 20 - but so what? The statement is not actually wrong but what sense is there in making it?

just to simply express a reduction. Does it makes sense to you talk about the reduction in terms of a percentage of the total amount? If it is specified like that of course.

Percentages, used more than once in an argument need to be treated with care because people often try to pull a fast one that way.

Multiple 'percentage' reductions should be dealt with correctly, that is by multiplication.
Thus, 20% off then another 10% off is 0.8 X 0.9 (=0.72) or 72%, which means 28% overall reduction and not 30%.

This is just talking about a single percentage reduction, not multiple.

i.e.
a reduction of 5pp
a reduction of 25%
a reduction of 5% of the total
 
NotAnEngineer said:
How would you word it??

Now let's choose 15 out of the original 20. So that would be 15 out of 100 or 15%

to start with...
 
  • #10
"Figures don't lie but liars figure."
 
  • #11
pgardn said:
Now let's choose 15 out of the original 20. So that would be 15 out of 100 or 15%

to start with...

Okay, I said that much.

Go on...
 
  • #12
The fact that you are needing to query it means that the statements could probably be made in a better way and are open to misunderstanding. What is the point of all that preamble if the information is that the five in your hand represent 5% of the original. Are they a "reduction"? I don't see how; they are just five items. What about the other 15 items, of the 20 that were originally taken out? Are they then put back, amongst the 80 still on the shelf? The scenario is a bit baffling.

What would be the purposes of stating the situation in the two different ways? To give information or to cloud the situation?
 
  • #13
NotAnEngineer said:
Okay, I said that much.

Go on...

No actually I did not get that from the original statements.
 
  • #14
Then, and this may be my problem, I have no idea what a reduction percentage is.
 
  • #15
sophiecentaur said:
The fact that you are needing to query it means that the statements could probably be made in a better way and are open to misunderstanding.

I think there are many ways to express it, and as to which one is better, that is an opinion.

Im just trying to figure out if the general idea of expressing a reduction, as a percentage of the total, makes sense to you.



What is the point of all that preamble if the information is that the five in your hand represent 5% of the original. Are they a "reduction"? I don't see how; they are just five items. What about the other 15 items, of the 20 that were originally taken out? Are they then put back, amongst the 80 still on the shelf? The scenario is a bit baffling.

What would be the purposes of stating the situation in the two different ways? To give information or to cloud the situation?


You're thinking about it too much. Again, I really just asking if the general idea of expressing a reduction, as a percentage of the total, makes sense to you.
 
  • #16
pgardn said:
Then, and this may be my problem, I have no idea what a reduction percentage is.
The way figures are presented can be shameless. "Five times less pollution" - wtf? What's wrong with "One fifth of the pollution"?
 
  • #17
pgardn said:
No actually I did not get that from the original statements.

"If I reduce that number to 15 then I would have 15%"

i.e. 15 out of 100


Regardless, does the idea of expressing a reduction, as a percentage of the total amount, make sense to you??
 
  • #18
pgardn said:
Then, and this may be my problem, I have no idea what a reduction percentage is.

The phrase "reduction percentage" was never used.

This is referring to phrase "reduction, as a percentage of the total amount"
 
  • #19
NotAnEngineer said:
Again, I really just asking if the general idea of expressing a reduction, as a percentage of the total, makes sense to you.

It's the way prices are advertised in shop windows so I am used to it. I wouldn't like to see it used in a scientific argument except, perhaps, in a summary. Bearing in mind how few people actually understand percentages (this is true) then I would say many people are duped when information is presented in those terms.
 
  • #20
NotAnEngineer said:
The phrase "reduction percentage" was never used.

This is referring to phrase "reduction, as a percentage of the total amount"
That would be a reduction of 5 items, or a 25% reduction%.

My bad I guess. What is the bolded?
 
  • #21
sophiecentaur said:
It's the way prices are advertised in shop windows so I am used to it. I wouldn't like to see it used in a scientific argument except, perhaps, in a summary. Bearing in mind how few people actually understand percentages (this is true) then I would say many people are duped when information is presented in those terms.

So which way would you rather see it phrased??

A reduction of 5pp
a reduction of 25%
a reduction of 5% of the total

Or anther way??I don't really see where you are coming from saying that one is more misleading than another. You of course have to know something about percentages to understand either one, but as long as you do, I would think you could figure either one of them out with regards to what it is saying.
 
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  • #22
NotAnEngineer said:
"If I reduce that number to 15 then I would have 15%"

i.e. 15 out of 100Regardless, does the idea of expressing a reduction, as a percentage of the total amount, make sense to you??

It does now after reading the posts. I personally did not get your ie to start with. Maybe that's my problem. I have read too many of these types of problems that are used as tricks. Dont take it personally if you wrote it. If you have enough interest to post, I have enough interest to answer honestly.

Where did the 25% come from?
 
  • #23
pgardn said:
That would be a reduction of 5 items, or a 25% reduction%.

My bad I guess. What is the bolded?


That is a typo. Now that you know that, can you go back and answer the question.

Thanks in advance.
 
  • #24
pgardn said:
It does now after reading the posts.

Where did the 25% come from?

A reduction of the original 20 out of 100, to 15.

5 of 20 = 25%

Or a 25% reducion
 
  • #25
pgardn said:
It does now after reading the posts. I personally did not get your ie to start with. Maybe that's my problem. I have read too many of these types of problems that are used as tricks. Dont take it personally if you wrote it. If you have enough interest to post, I have enough interest to answer honestly.

Where did the 25% come from?

It is no trick I all, I promise.

Just if someone were to say to you "a reduction, as a percentage of the total amount"

Would you be able to follow what that means? I am just trying to get a general feel that if I expressed something like that, should the average person (who understands basic math of course) be able to pick up on what I am trying to say.
 
  • #26
NotAnEngineer said:
A reduction of the original 20 out of 100, to 15.

5 of 20 = 25%

Or a 25% reducion

Ok. I did not get that before. And I had no idea that was a typo.

So we are comparing 20% to 15%. There is a 5% difference.

Or a 75% change in percentage. 15/20 = .75

Kinda see what I am talking about? You said reduction so I guess that means subtract the percentages. I am not clowning on you. I have seen too many ways of wording as Sophoc... noted that are used to emphasize something that really is not there, or just too cloud a situation. So yes I now get it.

I am also not an expert at writing questions. I just know what I do understand clearly and what I do not see clearly. I have hated everything I have ever written because I read too much. When I compare my writing to others I feel inclined to slap a pie in my face.
 
  • #27
NotAnEngineer said:
So which way would you rather see it phrased??

A reduction of 5pp
a reduction of 25%
a reduction of 5% of the total

Or anther way??


I don't really see where you are coming from saying that one is more misleading than another. You of course have to know something about percentages to understand either one, but as long as you do, I would think you could figure either one of them out with regards to what it is saying.

I would prefer information to be presented in a way that is relevant and makes sense. Either the 25% figure is important (relating to the 20 items) or the 5% figure (relating to the total) - or, indeed, the initial 20% reduction (relating to the total). Whichever you tell me is the relevant message (and the source of the information would know that, I presume) is the one I want. Your original story has two stages to it so there are three 'transitions' that can be described - overall, or the intermediate steps. You are trying to 'sum up' the process - or some part of it - so choose that particular option and make it clear.

Failing that, the numbers speak well enough for themselves, don't they?
 
  • #28
sophiecentaur said:
I would prefer information to be presented in a way that is relevant and makes sense. Either the 25% figure is important (relating to the 20 items) or the 5% figure (relating to the total) - or, indeed, the initial 20% reduction (relating to the total). Whichever you tell me is the relevant message (and the source of the information would know that, I presume) is the one I want. Your original story has two stages to it so there are three 'transitions' that can be described - overall, or the intermediate steps. You are trying to 'sum up' the process - or some part of it - so choose that particular option and make it clear.

Failing that, the numbers speak well enough for themselves, don't they?
I other words, you don't care how its presented, and long as its specific in what it is saying??

Ill make up an example, say you have unemployment numbers, and the unemployment dropped over a certain time. (This is assuring a constant sized workforce)If a year ago unemployment was 6%

Now it is 4%

If were to say that unemployment was reduced by 2% of the total workforce, would you be okay with that??Keep in mind I could also say:
-unemployment was reduced by 2pp
-unemployment was reduced by 33%

^^ those are all saying the same thing, but my question is regarding to the way I originally expressed it... unemployment was reduced by 2% of the total workforce
 
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  • #29
My answer is that it depends upon what you want to emphasise. 2% is probably a better figure if you are trying to give an idea of the cost of benefit payments but 33% is good if you want people to think you've done a good job as prime minister.
Either figure, on its own, is not enough and I would say that it is not necessarily a good thing to over-condense information into just one figure. To be as fair as possible, you should often include more figures - something about the total workforce size, for a start.
This thread has gone to prove that people couldn't agree about which single figure to present - or what it would actually mean. This proves my point, I think.
Less is not always more. . . . .
 
  • #30
sophiecentaur said:
My answer is that it depends upon what you want to emphasise. 2% is probably a better figure if you are trying to give an idea of the cost of benefit payments but 33% is good if you want people to think you've done a good job as prime minister.
Either figure, on its own, is not enough and I would say that it is not necessarily a good thing to over-condense information into just one figure. To be as fair as possible, you should often include more figures - something about the total workforce size, for a start.
This thread has gone to prove that people couldn't agree about which single figure to present - or what it would actually mean. This proves my point, I think.
Less is not always more. . . . .

You're over complicating the issue, which I fully expected someone to do.

Im not trying to emphasis one thing anymore than another. Just simply trying to express the reduction in an understandable way. I think either figure on its own is enough, if specified correctly.

This is just a simple question... "does expressing a change in value, as a percentage of the total amount" make general sense. Yes, or no. You do not need to know anything specific about the total (i.e. the size of the workforce) to answer that question, it is an irrelevant value with regards to the question.
 
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