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percentages

percentages

percentages

(OP)
Say a project is estimated for a dollar and the actual price is two. What is the best way of expressing this fact using percentages rather that dollars? Please assume a non-technical audience. I like 200% because it looks higher, but I do not wish to falsely convey the project exceeded the estimate by 200%. For the sake of clarity, I opted to use both figure. "The final price was 200% of the estimate, or 100% over." Alas my attempt at clarity has failed, since my test readership (my wife and son) were 100% confused by my use of two figures. "Which one is it?"

What's your advice? Thanks.

RE: percentages

I think it would be less confusing if you say it is 100% over.

Like if gas price goes up from $1.00/gal to $1.50.  Probably its better to say the price increases 50%.

RE: percentages

Why confuse the audience with possibly ambiguous numbers? Speak plain English ... "The final price was double the estimated price"

cheers
Helpful SW websites FAQ559-520
How to find answers ... FAQ559-1091

RE: percentages

But you dont sound as smart if you use plain english  :)

RE: percentages

(OP)
I used the one and two dollar figures for an example. "Double" understates the real outcome.

RE: percentages

My only input would be... put as much information as you can.  It is always confusing.  

If I say the price of gas goes up 50% (less than 100%), most people will understand it.  But if the price goes up from $1.00 to $2.50 and you say the price goes up 150%, I bet cha a lot of people would think the price is $1.50.  So I say put the actual number on the top of the %.

RE: percentages

Just my thoughts:

I would say that if you want to be neutral, then just state the numbers.

"The estimate is $1. The actual price is $2."


If you want to highlight the fact that things are more expensive now, then use the highest number in whatever units that give the impression of a large increase.

"The actual price is 200% of the original estiamte. This increase is due to ..."


If you want to minimise the fact that things are more expensive, then use the smallest number in whatever units that give the impression of a small increase.

"The original estimate was 50% of the actual price. This increase was due to..."

"Do not worry about your problems with mathematics, I assure you mine are far greater."   
Albert Einstein
Have you read FAQ731-376 to make the best use of Eng-Tips Forums?

RE: percentages

I still say use plain English.

If you are trying to communicate (with clarity) to a non-techincal audience, you should use language which they will understand;
"The final price (cost ?) was twelve and a half times the estimated price."

As was proved with your test audience, numbers (especially percentages) can be too easily mis-understood but, if you really want to bamboozle them, you could then back up the plain English with large percentage numbers ;
"That's 1,250% !!!"

cheers
Helpful SW websites FAQ559-520
How to find answers ... FAQ559-1091

RE: percentages

It's all about spin.

"The original estimates were 50% of the final cost."

Or

"The project was on budget."  With a a foot note in 2-point type explaining that the budget was re-baselined the day before the contract was closed.

RE: percentages

If you want spin, there's always ‰.
Percentage has nothing on permillage.

RE: percentages

IF you use percentage, you MUST mention the basis for the percentage.

Percentages appear to have more meaning when it is less than 100%.  If over 100% I think terms like "2-fold increase" or "threee times as much" convey more meaning with less chance of confusion.

RE: percentages

(OP)
The basis was the estimate, I thought that much was clear. "2-fold increase" suffers from the same potential reader error. I read it so the "2-fold" only applies to the "increase" so your total is 3 times the estimate. But will your average non-technical reader get the distinction?

RE: percentages

I would be totally stunned if any non-techincal reader were to apply "2-fold increase" as you suggest. In fact, no disrespect intended, I'm amazed that you did. I would never have thought of that interpretation.

cheers
Helpful SW websites FAQ559-520
How to find answers ... FAQ559-1091

RE: percentages

How about,

Final costs were double the estimate.

Per Cor blimey.

If you really want to flag how much that was then say

Giving a total overspend of $xxx.

% etc will cause confusion to some, I had a similar conversation with Designer here on a technical report someone else had given him.  I would like to think most Engineers (and probably bean counters) would understand the difference but there are a lot of other personel around who may not.

RE: percentages

(OP)
Why are you amazed? What should increase mean to a technical reader other than the portion above? If I said the original $1 had increased by a $1 would anyone not understand the new price was $2? And if I said the price had increased by a factor of 0.5, would anyone take that as an overall decrease?  

RE: percentages

The wording used in your last post leaves little room for misunderstanding ... because you used plain English. smile

However your interpretation of applying the "2-fold increase" (in your previous post) amazed me because if I applied that logic to the $1 example I would have $3 ... I don't understand how a "2-fold increase" can be interpreted to mean "3 times the estimate".

Two-fold = double.
http://dictionary.reference.com/browse/double

If someone ate a double portion of something, did he/she eat two or three portions?

cheers
Helpful SW websites FAQ559-520
How to find answers ... FAQ559-1091

RE: percentages

(OP)
Estimate= $1. 2 fold = 2X the estimate = $2. Increase means to make greater. If $1 is made greater by $2 the result is $3. (note that using multiplication rather than addition in this context would lead to an answer with units of $^2, not a very useful result)

"If someone ate a double portion of something, did he/she eat two or three portions?"

It means they ate 2 portions. If they had instead eaten a double portion increase after already consuming a single portion, then they had 3 portions. The key difference is the word increase.
 

RE: percentages

rofl I don't know how to argue with that "logic" so I'll just re-offer my original suggestions as being the clearest & least ambiguous;
"The final price was double the estimated price"
"The final price (cost ?) was twelve and a half times the estimated price."

I wish these fora had an "Instant Survey" function.

cheers
Helpful SW websites FAQ559-520
How to find answers ... FAQ559-1091

RE: percentages

Some of this may be a UK US thing.

Can't remember exactly the terms but in the analysis we used to do at my last place (UK) we used a factor.  

The US companies we worked with used margin, the amount over.

We'd have a safety factor of 1.5 while they had a margin of .5.

Caused confusion at times.

RE: percentages

I've always had to concentrate real hard to figure if the percentage should be related to the original number or the final number. Glad to see I'm not the only one with an intrinsic ability to misinterpret these kinds of statement!

RE: percentages

Hmmmm,

My tri-fold wallet is designed to be folded in two places. When folded, it becomes three times as thick. Oh well, it's empty anyway.

RE: percentages

Just goes to show that numbers & words can be twisted to suit just about any scenario.

cheers
Helpful SW websites FAQ559-520
How to find answers ... FAQ559-1091

RE: percentages

I always found percentages confusing when learning them as a kid.  The problem is that when you start referring to "percent change" you can introduce an ambiguity since it becomes important what the "subject" of the percentage is.

For example, if you add 20% to a number, then subtract 20%, you don't end up with the original number, which can be confusing to the layman.

100 + 20% = 120
120 - 20% = 96

Go figure.

Don
Kansas City

RE: percentages

That's because the layman doesn't realize that implicit in the equations are:
100+20%(of 100) = 120
120-20%(of 120)=96

RE: percentages

I interpret "two fold increase" as three times the original amount.

Out of curiousity I asked 3 people what they thought it meant. One person said it meant three times the original amount, the other two said it meant twice the original amount.

It's clearly a very bad phrase that should never be used.



RE: percentages

"You can prove anything with statistics, 38% of all people know that."  - Homer Simpson

RE: percentages

I hate percentages more than anything else.  If I had to say one thing has been the bane of the engineering profession it would have to be percentages.  My vote is always use hard numbers.  I cant tell you the amount of times I have had to explain to the egghead phDs, MBAs, and even senior engineers that audit me that the percentage that they are using is incorrectly applied because the units are totally wrong.  It seems to easy to lose the units and relationships, so I never ever do.

RE: percentages

I just read something in a UK engineering mag (PE) which touched a nerve and is relevanr here.  The correspondent asked

Quote:

Don't we already pay 70% tax on our fuel?

Actually we do not.  Instead, 70% of the price we pay for our fuel is tax.  In terms of additional cost, that's a 333% tax.

RE: percentages

If we buy services at £100/unit and sell at £140/unit, is the contribution to the bottom line 40% or 28.6%?

RE: percentages

This is the same as my fuel price post.  If you work out your percentages using the selling price, 100% is your maximum figure (assuming you buy for nothing and all the price is profit).

RE: percentages

This whole topic reminds me of choosing which math to take at VI form (last two years of high school).

The hardest/most comprehensive math was 'double A level'.

This came in 2 flavours.  Pure and Statistics or Pure and Applied.  Given my goal of being an Engineer and it's overlap with Physics I went for Pure and Applied.  Pure and Applied was also widely considered more challenging than pure and statistics.

Funny thing was when those of us taking applied came to do the little bit of statistics (and probability) required as part of pure math we struggled.  I can't recall the details but the irony wasn't lost on us!

RE: percentages

How about, "The final price came in at $100, double (or twice)the estimated price". Clear simple understandable English

Naresuan University
Phitsanulok
Thailand

RE: percentages

I have a problem along similar lines. The statement I have so far says:
"A maximum value for the setpoint is entered by the operator. If the calculated value is greater than the maximum value, the setpoint will be set to the maximum."

For the next sentence I am looking for an elegant way to say "if a tank is taken off-line the maximum value allowed will be 70% of what it was before when both tanks were on-line"

Would saying "the maximum value is reduced by 30%" be adequate or would that introduce confusion?

RE: percentages

Stevenal, either way is correct, but neither may be appropriate for any given audience.  

My preference for indicating an increase would be "The actual price was 2.5 times the original estimate of $1".  For a decrease, "It was half the original estimate of $1"; using a decimal "0.5 times" would be correct, but it would mentally bug a lot of people, technical or not.

Jim Sykes, P.Eng, GDTP-S
Profile Services
CAD-Documentation-GD&T-Product Development
www.profileservices.ca

RE: percentages

So far this discussion has mostly been about how to accurately convey increases, but MechNoth brings up (no pun intended) decreases.  Count me as one of those who are bugged by using multiplication to convey decreases: "10 times fewer" or "6 times lower", etc. I'm pretty sure the writer means 1/10th and 1/6th, but the actual reduction would be 9/10ths or 5/6ths.

On a related note, we received a flyer from a local retailer in the mail yesterday advertising "an extra 20 to 10% off". That's not wrong, but I would have said "10 to 20% off".  Or maybe that's how they say it in New York--the local (Chicago) retailer was just bought out by a New York company.

I know there are much greater problems in the world than this but it's nice to vent. I'm 1/5th less stressed now. That's a 20% reduction. Thanks!

RE: percentages

So your frustration level is now only 80% of the original value.

RE: percentages

I'm curious ... what is the % symbol derived from?

Chris
Systems Analyst, I.S.
SolidWorks 06 4.1/PDMWorks 06
AutoCAD 06
ctopher's home (updated 06-21-06)

RE: percentages

Cool! Thanks!

Chris
Systems Analyst, I.S.
SolidWorks 06 4.1/PDMWorks 06
AutoCAD 06
ctopher's home (updated 06-21-06)

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