Talk:Percentage

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[edit] No history of % being used?

This is wikipedia, not a math textbook. Expand the article. --172.159.137.89 00:30, 26 January 2007 (UTC)

[edit] Other

i like where this article is going. i'd like to see some examples how percentages can be misleading...how two opposite conclusions can be drawn from the same data...how politicians mislead the public. Kingturtle 07:11 Apr 13, 2003 (UTC)

[edit] about the "risen by 10%"

Percentages are always relative, because they are basically a type of fraction. Just because most people get it wrong, doesn't mean we should condone it. Financial reports always speak of "percent points" or just "points" or say what the rate changed to. -- Tarquin 16:33, 28 Aug 2003 (UTC)


[edit]  %10 or 10% ?

Am I the only one that likes to use the percentage sign before the number? Is there a general usage of the percentage sign? I know in html, if you want to use a space character in a link you would use something like %20 which has totally different meaning in that context (hexadecimal for 32, the ascii number for space). But I've always liked using the percentage sign before the number. It gives the reader a warning.. "beware, the number you are about to look at represents a fraction multiplied by 100". Otherwise, I think I tend to ignore the sign (or reverse it in my head if I do notice). But now that I've actually seen the preview, 10% looks more correct. Hmmm. -- Root4(one) Section 2.1. 19:51:24, 1 Oct 2004 (UTC)

I've never seen that before (the prefix percent).  :-) - Omegatron 20:32, Oct 1, 2004 (UTC)
The article says
some examples on the Internet that have the symbol precede the number. This may have something to do either with a firm's typographic style, or perhaps an international standard relating to the metric system.
Where can I find examples like that (different from the above mentioned HTML usage), and which international standard is being referred to? AxelBoldt 21:08, 31 May 2005 (UTC)
The order "%10" is the standard one in Turkish. See for instance the exchange-rate banner labelled "PiyasaNet" on [1]. The writing order reflects the spoken order: "percent" is yüzde (literally: "on [one] hundred"), "ten" is on, and "ten percent" is yüzde on.  --LambiamTalk 22:00, 29 September 2006 (UTC)
Same in Basque. %6 matches spoken ehuneko sei ("hundred-of six").

[edit] Can we have sq. rt. (2)%, pi %, etc.?

Does it require all percentages to be rational numbers? That is to said, can we have sq rt (2)%, pi %, etc.?

As from its definition, it stated that "to express a proportion, a ratio or a fraction as a whole number ...".

Please advice, thank you.

Alan

In normal use the percent sign is preceded by a number written out in decimal form. Clearly, to actually do that requires that one use a finite decimal expansion, which always gives a rational number. However, it is often a rounded form. There is no reason to assume that this stands for an actually rational number. Take for instance the text: As early as the 19th century BC, Babylonian mathematicians were using π = 25/8, which is within 0.53% of the exact value. It is actually within X % of the actual value, where X = 100 × (1 − 25/(8π)) = 0.5281605675654.... This is an irrational amount. But to give an impression how good the approximation of the Babylonians was, we only need one or two decimals of the infinite expansion. It would be silly to write "100 × (1 − 25/(8π)) %", as this defeats the whole purpose of giving an impression, and is moreover more complicated than the equivalent expression "1 − 25/(8π)".  --LambiamTalk 22:43, 29 September 2006 (UTC)

[edit] Space or not?

Is there to be a space between the procentage, and the per cent sign? In this Wikipedia article, most English news articles, and The Chicago Manual of Style, there is not one, but according to ISO 31-0 (an NIST Special Publication 811 quotes it in secton 7.10.2), there should be a space. Which is the correct notation?

Unfortunately, as discussed previously in the Manual of Style archives, there's an inconsistency between the overwhelmingly more common English practice of having no space, and that recommended by ISO 31-0.
Personally, I'm heavily in favour of having no space as I think it looks much better from a typographical perspective. In fact, until I found out about ISO 31-0, I wasn't even aware that it was an issue: as far as I knew, not using a space was simply the correct way to format percentages. I'll try to see if I can dig up any typographical advice on the subject.
One thing that should be noted is that if people decide to use a space between the number and the percent sign, it must be a non-breaking space, otherwise you'll get scenarios where the number appears at the end of a line of text, and the percent sign on the next line. Cmdrjameson 22:34, 31 July 2006 (UTC)
Thank you for dropping by and replying! Myself, I definitely prefer without space - it's easier to read, and it never breaks down to two lines, no matter how careless the writer is. The reason I noticed the issue when Cmdrjameson ran his bot was because I'm used to Microsoft Word (back when I still used that) constantly telling me to put a space inbetween, which I constantly refused to do. Perhaps we should just leave it to the style guide and pray this obscure international standard corrects itself in a future revision? Jobjörn (Talk ° contribs) 02:24, 1 August 2006 (UTC)

At first, we should figure out whether the "per( )cent" is a unit or not. Is it a unit or symbol? If it is a unit, there is a general rule: "Always use figures when a unit of measurement follows (e.g., 5 A)" [2]. Furthermore, it should follow the space rule given above. The famous TeX typography, which collects and establishes the best document formatting standards, enforces the space between value and unit see units pdf by producing nice thin spaces. The document shows that all units have a name and a symbol and the symbols are used for writing down quantities. A particular must have a strong excuse to violate a general, since adding exceptions complicates the rules. Arbitrariness in rules produces garbage, chaos -- the world without any order and everything is exception. So I suggest that the article or the rule telling "Most guides agree that they always be written with a numeral, as in '5 percent' and not 'five percent'" be corrected. I recommend to follow the simple general rule: textual 'Five percent' at the beginning of sentence and figural '5\,%' elsewhere. --Javalenok 12:14, 8 November 2006 (UTC)

Based on the discussion above, I've tried to clarify the subject. I've also moved the section from Percentage#Word_and_symbol to Percent_sign#Spacing and added a link from the former to the latter. After all the question of spacing is irrelevant to the concept it has to do with the symbol. --Alf 20:34, 5 January 2007 (UTC)

[edit] Whole number only?

Re a comment made at the reference desk ([3]), the definition as it stands seems to imply that only whole number (i.e. non-negative integer) percentages are percentages. This contradicts most dictionary definitions I can find; should it be reworded, or am I missing something? Ziggurat 02:39, 29 June 2006 (UTC)

Not only should it be reworded, at least one example of a non-whole percent should be added. Currently the entire article suggests that only whole percentages are used, which is simply wrong. Melchoir 02:49, 29 June 2006 (UTC)
What's more, since percentages are so common in statistics, it is very common to show the accuracy of the number as trailing decimals, even when they are zero. (Just look at this: [4] ).
Or look at the percentages here: http://www.bulletinph.com/395-candidates-pass-prc-exam-for-architects.html :{ --LambiamTalk 18:54, 3 July 2006 (UTC)
I was often asked at work to use percentages with one decimal place, such as 54.6%, but I didn't like doing it. (I was preparing reports about the money contributed towards various fundraising goals.) The extra decimal place gave to the reports the appearance of greater accuracy, which my boss liked. However, I felt that the extra decimal place hurt the reports, because the percentages were more difficult to read. For example, 54.6% is not as easy to read and understand as 55%. The purpose of percentages, in my reports and in most cases, is to explain the import of a long number like $38,727.50 by giving its equivalent as a short number like 55%.
In other situations it might be appropriate to use a percentage with one decimal place. In effect, the increment of measurement would not be one percent, but instead would be one-tenth of one percent. The measurement would not be per hundred, but per thousand. There is an old symbol for "per thousand," which looks like the percent sign with another zero. (Perhaps */oo is the best imitation I can type.) However, current usage is to say 54.6 percent instead of 546 per thousand.----
The symbol is ‰ and is called permille.  --Lambiam 08:27, 27 November 2007 (UTC)

[edit] Percentage vs. percent sign

Should these be split up? I notice that an anon has added the punctuation infobox here, but aside from one paragraph the whole article is about the concept, not the symbol. Is there enough content for a separate percent sign article? Ziggurat 22:39, 17 July 2006 (UTC)

[edit] punctuation infobox?

IP 24.131.125.172 added the punctuation infobox, which I find not particularly useful for this article. I removed it once, but it was re-added. Comments? Paul August ☎ 22:47, 17 July 2006 (UTC)

See above. The solution would be to split up the article on percentage the mathematical concept and percent sign the sign used to represent it, and then add the infobox to the latter only. Ziggurat 22:54, 17 July 2006 (UTC)

I hadn't noticed the section above when I made this comment. Yes separating the article might be a good solution. If you want to do this, please do. I doubt anyone will object. Paul August ☎ 23:13, 17 July 2006 (UTC)

Doing so now... Ziggurat 23:36, 17 July 2006 (UTC)

[edit] Unicode?

As I noticed many other articles where the topic was a symbol, letter, or character stated the unicode value of that character, should that not also be listed in this article as well? -Aknorals 10:49, 17 August 2006 (UTC)

This article is about the concept of the percentage, not the symbol. For that, you'd be looking for percent sign, which does indeed have the unicode value. Ziggurat 10:57, 17 August 2006 (UTC)
Actually, I was redirected here from "percent".. I had somehow figured that sense the word "unicode" didn't appear on the page, that the article also included info on the sign, but not the unicode of it... -Aknorals 12:42, 17 August 2006 (UTC)
Oh my, perhaps I should have read the first line of text? Sense I browse wikipedia a lot, I sometimes ignore that line unless it's in italics (indicating a different article) -Aknorals 12:48, 17 August 2006 (UTC)

[edit] Section Changes is wrong! There is no such thing as different usages in percentage!

"Due to inconsistent usage, .... to many people, any other usage is incorrect. .... In the case of interest rates, however, it is a common practice to use the percent change differently"

This section is wrong. Percentage have only 1 usage: representing a value as a N/100 fraction of another value. There is no other magical usage of it. Interest Rates is no exception. Then it is said 50% rate increase, from 10% to 15%, It is referring to the rate value. Then it is said it has increased by 5% (and not 50%) it is referring to the interest, NOT the rate. There is no difference in saying "10% of interest" and "the interest rate is 10%", but there IS difference between saying "+5% of interest rate" and "the interest rate is +5%". There is NO magically different usage in percentage of percent. The confusion is about meaning (interest X interest rate) and NOT different usages!!! I am trying to fix it but people are continuing to revert it. --SSPecteR

Unfortunately this incorrect usage does exist: [5]•[6]•[7]•[8]•[9]•[10]•[11]•[12]•[13]•[14]•[15]  --LambiamTalk 04:54, 1 November 2006 (UTC)
Then someone should define this "usage" as wrong in the article. As it is it appear the 2 are equally right. And when it say "it is a common practice to use the percent change differently" it don't define what usage is the different use. --SSPecteR
Well, perhaps "confusing" is a better term than "wrong"; I meant to echo the viewpoint of some people that this is incorrect usage. In any case, this usage is at best ambiguous. The text of the article is perhaps not optimally clear, which is also the case for the rest of the article.  --LambiamTalk 08:26, 1 November 2006 (UTC)

[edit] Symbol

The article states that the symbol is an abbreviation of the Italian "per cento". How so? As a backwards P and a closed-up c? I have always thought that it was a rearrangment of the numerals 1, 0 and 0 (forming "100"). Perhaps someone can give a reference here. — Paul G 12:21, 1 November 2006 (UTC)

See the article Percent sign, which is referred to by a wikilink in that sentence (although it is not clear to me that the further reference provided there entirely supports the iconic evolution as sketched).  --LambiamTalk 14:01, 1 November 2006 (UTC)
I think that article is wrong. See my arguments in the discussion there. sspecter 1 Novemver 2006

[edit] 110%

I'm often hearing of the term 110% in various places (at work and on television). Is this strange mathematical phenomenon mentioned anywhere in Wikipedia? --Rebroad 21:29, 11 November 2006 (UTC)

This is not necessarily strange. If something grows by 10%, then afterwards it is 110% of the old value (100% + 10% = 110%). It can also refer to a difference: Suppose your snark hunting licence used to be ₤6,200 for a season, but they raise the price to ₤13,020. Then you can complain about this scandalous and ridiculous price raise by ₤6,820 (₤13,020 − ₤6,200), by saying that the price more than doubled. If you want to be precise, you can say it increased by a whopping 110%. The way you arrive at this number is that 6820/6200 = 1.10, which is 110 times 1/100, or 110%.  --LambiamTalk 12:55, 12 November 2006 (UTC)
I realized you probably were referring to people saying things like: "She is giving it 110 percent." I told them a million times not to exaggerate, but they won't listen. If I hear this one more time I will literally explode. It's called hyperbole, although I think there is a semantic aspect of "beyond the call of duty": where others would be done, she gives it an extra effort.  --LambiamTalk 13:25, 12 November 2006 (UTC)

[edit] Problematic text

I have moved the following text here from the article:

The number 100 is chosen as an arbitrary standard. It is unclear to even some scientists that 100 is not a factor or coefficient, but a notation. That is to say, percentages are calculated, for example, like this:
success-% = successes / trials, e.g. 15% = 0.15 = 150/1000
and not
success-% = 100 × successes / trials, e.g. 15% = 0.15 is not 100 × 150/1000 = 15 (1500%)
The latter would actually multiply the result with 100, rather than denote it as a percentage.

I have various problems with this text. First, it was placed (and after I deleted it, re-placed) in the section entitled "Word and symbol", but it is neither about the word (that is, percent), nor about the symbol (%). My main problem, however, is that even after multiple readings I cannot figure out what the text is attempting to say. Of course the choice of the number 100 is not "arbitrary". Clearly, 67 would have been a terrible choice, and we'd never have heard of (and certainly not had an article about) persexagintaseptemage. The point of using 100 is that you just shift the decimal point, and don't have to do any difficult multiplications and divisions. Why not 10 or 1000? One of the points of using percentages instead of fractions is that in many cases you can round the percentage to a whole number and not lose too much precision. The multiplier 10 is too small for that, while higher powers of 10 give too many digits. Usually 100 is just right. So it is not arbitrary. It was also not chosen "as a standard"; any standardization took place centuries after percentages became firmly entrenched.

The use of "some" in "some scientists" is a weasel word. Does the author have a bone to pick with a scientist? If this is something notable, we need a reference. Now it may indeed be unclear to some scientists that 100 is not "a factor or coefficient", and guess what: here is one! I just don't know what it is supposed to mean that 100 is or is not "a factor or coefficient, but a notation". Of course "100" is a notation, but it is not just a notation: it is a notation for a number. Whether it is a factor depends on a possible formula in which it occurs. Stating in isolation, without reference to a specific formula, that it is not a factor, is simply meaningless. It is explained in the article that percentages are a way of expressing numbers as fractions of 100. You can explain % as standing for "per 100", or more symbolically "/100", so 15% = 15/100. And that is of course where the name comes from: per cento is Italian for "per 100". In the formula 15/100, clearly 100 is not a factor, and one would be hard-pressed to find "some scientists" who claim otherwise.

The next formula, with the typographically and linguistically horrible "success-%" is hard to follow; if this is supposed to be an example, it does not explain how the variables in the formula are related to the numbers in the example. In any case, if S is the number of successes on a run of T trials, and someone has the task to find the number P such that the percentage of successes is P%, then they should calculate P = (S/T) × 100. For example, if S = 150 and T = 1000, P = (150/1000) × 100 = 15, so then the answer is 15%. There is nothing wrong with this, and the number 100 is clearly a factor in the formula for P. There is nothing wrong with this, and if someone has learned it this way long time ago and wants to brush up by reading our article, the suggestion produced by the second "and not" formula that there is something terribly wrong with this is only confusing.

In the last example it is of course true that 15% is not the same as 15; however, isn't that a strawman?  --LambiamTalk 00:18, 5 January 2007 (UTC)

A rather convoluted commentary, but the point is rather simple. Often we see texts with formulas like "conversion = 100 × output/input". This would imply that conversion is 100 times the proportion, rendering formulas like "output = conversion × input" invalid. 100 is not a special number; it is chosen to represent fraction, not actually modify their value. Per cent means "/100", therefore 15% is 15/100 or 0.15. You cannot say that 100 × 15/100 = 15% — the correct formula is 15/100 = 15%. That is to say, converting to percentage doesn't involve a multiplication by a mathematical coefficient of 100. --Vuo 16:36, 5 January 2007 (UTC)
But isn't X = (X×100)%? Suppose that, instead of the arbitrary number 100, they had chosen 67 a long time ago, and we were stuck with it. Using $ as the symbol for persexagintaseptem, we have that 1 = 67$. Now suppose the task at hand is to express the value 0.597 as a persexagintaseptemage. How should one go about doing that?  --LambiamTalk 20:44, 5 January 2007 (UTC)
You are correct that X = X × 100%. It is correct to write 100% × 15/100 = 15%. Since X × 100% = X × 1 = X, the operator × 100% does not modify the value. It is incorrect to write X = 100 × X. --Vuo 19:09, 6 January 2007 (UTC)