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Feedback on html coding for sample mean


Margaret MacDougall <[log in to unmask]>


Margaret MacDougall <[log in to unmask]>


Fri, 28 Oct 2005 16:39:51 +0100





text/plain (805 lines)

Dear all stat users


Earlier this month I sent the message below to allstat.  I received a variety of replies confirming that there is not a stand alone good html coding for creating the character for the sample mean which I wished. A big thank you to all who kindly replied.



Most of the suggestions pointed me to extension to html which could not be supported for universal use with my electronic system or were suggestive of a little overkill for one character.  I did try the suggestion made under reply 6 but the outcome looked a little out of place in the middle of the rest of my text.


In the end I used a simple draw facility to create the 'x-bar' symbol and was able to embed it in my text by capturing the image and pointing to it via a URL.  This was very easy to do and I was surprised to discover that the resultant character looked very pretty, much better than would have been possible had I used the Equation Editor in MS Word to create my image.


Necessity is the mother of invention!





Previous request of 13 October



I would be most grateful for suggestions on how best to code the conventional symbol for the sample mean (which I am taking to be a small x with a bar immediately above it) in the language of html.


At present, I am using the following approach:


<style type="text/css">
#overline {text-decoration: overline}
 <div id=overline>x,</div>


However, this tends to give a rather make-shift result, as the 'overline' tends to sit rather aloof from the x. Moreover, the character is forced onto a new line and therefore is not embedded in my sentence as wished.  


I have consulted several good html books and discovered that whilst listings of characters and codes are made for many characters including latin letters with circumflexes, the character I am after is not represented. 


I am learning html almost from scratch and expect that a more experienced user could offer some code which has worked for them in the past.  


An alternative approach would be to capture as an image the result of creating my desired character using an MS Word equation editor. However, this seems a little far fetched for just one character.


Thank you in advance for your suggestions.


Best wishes






Reply 1

I don't think you can! I'm no expert on HTML either 

(and if there are any experts out there we'd love to be

 put right).


I've looked around a bit. There seems to be a consensus 

that you can't do much in the way of mathematical 

notation in standard HTML.


The nearest I've found -- which will only work in special

circumstances -- used a "proposed" extension to HTML called



The syntax given there was




with the caveat "Unfortunately most of the existing browsers do

not recognize the <MATH> tags, so you just get an x. The same

effect can be achieved in non<MATH> enabled browsers using a

<TABLE> construction; i.e.




which gives [display of x-bar on a separate line]"


See http://www2.sjsu.edu/faculty/watkins/html.htm


On my browsers (mozilla, firefox) the MATH did not work, and

the TABLE method put the x-bar on a new line, with the bar a

little too far above the x (just as described by Margaret).


I suspect, however, that the Opera browser does recognise MATH.

That's still no good, however, for people who don't use it!


The accented characters which are available in HTML at least

include those given as single entities in standard extended

ASCII character sets, such as iso-8859-1 which I'm using now,

and which your mail reader should render correctly, such as


         (only a selection) along with some stand-alone



These correspond to single ASCII codes and are not composed as

composite characters. Combinations of letter and accent which

are not amongst those available (e.g. above) in the character

set do not exist in HTML.


So, unless it's already a standard single character, you

cannot get it in HTML. In particular (apart from what may be

possible using <MATH>...</MATH>) you can't instruct HTML to

place an arbitrary mark as an "accent" to some other mark.


So, although the requisite stand-alone accent is available

in the iso-8859-1 set at position 175, the "macron" accent

(), and you can indeed get it displayed in HTML by entering




in your HTML, you can't as far as I can see instruct HTML

to display an "x" and then put a "" above it.


I agree that using Word + Equation Editor to get a bitmap

that you can import is overkill. And I'm personally no

admirer of the Equation Editor anyway. (Haven't we been

here before, and exactly on the "x-bar" topic? I recall that

pre-MedStats exchanges on this between Martin, John and me

about this were what first got us acquainted!)


Despite all this, I have two practical suggestions.


The first, for something as simple as x-bar, is simply to

write "x-bar". This will be readily understood, especially

if you initially explain that "x-bar stands for an x with a

bar over it; unfortunately this cannot be represented in

HTML so I'll just call it 'x-bar'".


The second is where you have occasion to use more than the

occasional mathematical symbol so that you need the reader

to see proper mathematical notation.


For web purposes, the ideal format for this is PDF. The

PDF display software Acrobat Reader is freely available

for most computer platforms from the Adobe website




So you just put a link to a PDF file in your web page,

and if the person reading it has installed Acrobat Reader

then they can see it exactly as you intended, and also

print it out. Again, the can download and save the PDF

file, so can readily refer to it later. Nowadays I assume

that nearly everyone has Acrobat Reader available so I have

no qualms about sending them PDF files.


The main issue for this suggestion is creating the file

in PDF format in the first place.


You might use Word (with Equation Editor) to create a Word

document which displays the mathematics more or less as

you want it.


<ASIDE>People who want it really right, however, will use

software intended for formatting to precise typesetting

standards, such as TeX/LaTeX and groff which are both free,

and available for Windows and Unixoid systems, and commercial

products such as McKichan's "Scientific Word", which also

claims to be able to export the results directly to HTML

"with mathematics exported as graphics or as MathML."


For LaTeX and groff too there is the possibility to do it

this way, using embedded graphics for equations (e.g. a

program called LaTeX2HTML, which is another free program).


The advantage of using software which incorporates this

approach is that the user, while preparing the document,

simply types in whatever makes it look right on screen.

Then the ecporting to HTML is a single operation, and the

software takes care of embedding the graphics when required.


However, for the real thing the PDF route is the way to go.

There is no limit to the complexity of what can be represented

in PDF, and no limit to the precision with which it can be

represented. (Whether the software you used to create it can

match this, however, is another question).</ASIDE>


Suppose, then, that you have a suitable Word document.

I've heard (though not experienced) that recent versions of

Word can export to PDF (or there's a converter).


However, if not (or not in your case), then you can print

to file using one of the PostScript printer drivers

(e.g. Apple LaserPlus).


Now you have to convert the PostScript file to PDF. Adobe's

commercial Acrobat Distiller will do this (and is the "industry

standard" since both PostScript and PDF are Adobe's creations).


Free options include ghostscript (whose ps2pdf utility

does the job) and somewhat more refined programs which

are specialised for the job such as Frank Siegert's



The resulting PDF file will display the mathematics as

well as (but probably no better than) it appeared in your

original Word document.


Hoping this helps -- and is not too discouraging!



Reply 2


Hi Margaret,


I think you might be unlucky with this one.


Here is an excellent webpage which covers some

html special characters:




but if you want to generate some for yourself then open my

attachment and click the button. You will find 'mean a' at

number 257 and 'mean c' at 275, etc but only a few letters

are catered for.


I image one could devise a method using DHTML and the

div structure but then it would all get a bit too complicated.



Reply 3


HTML doesn't fit for this :(

The graphics approach (for the whole equation usually) is the best I've 


to get round it, but it's a poor solution. 


I should look to see if an of the Unicode fonts carry these symbols, 

but I

haven't yet and not yet worked out how to address them in html



Reply 4


The official list of characters available in html is at:


It seems that overline exists only as an independent character.


A natural solution is unicode which has combining diacriticals:



Therefore, this should work:


<meta CONTENT="text/html CHARSET=UTF-8">

x <!-- should be x overline -->


but I find it is not supported on my browser.


Never use MS Word equation editor.  It produces very poor quality 


If you want to use an image, tex2im produces far better results and is 

much easier to use:



Reply 5


I faced the same problem a few years ago when I first began putting together the on-line stats text




After trying every HTML device I could figure out for X-bar, I finally gave up and simply used Latin letter M -- which for students is probably a better mnemonic for Mean than X-bar anyway.  For Greek-letter notations I resorted to usinng small images of the ones I chiefly needed:  lower-case mu, lower- and upper-case sigma, and lower-case chi.  There are other ways of doing Greek-letter notations, though they tended to give different results on different platform-browser combinations.  The real trick was in rendering complex formulaic structures in HTML.  I finally figured out it could be done via carefully crafted borderless tables.  The result is a bit clunky, though it gets the job done well enough.



Reply 6


Use <span> instead of <div>.  To get the bar from being so high, use  

a capital X and then reduce the font size.


That would come out to:


>> <style type="text/css">

>> #overline {text-decoration: overline}

>> </style>

>>  <span id=overline>x,</span>



Reply 7




Probably overkill for that particular query but when I need to write 


in html, I use a very useful cgi called mimeTeX:


Once installed, you simply write the LaTeX code as you usually would, 


the picture is generated on the fly. You can also leave it in the cache

(better if the page receives a lot of hits).


It's fairly easy to install and doesn't require TeX. Just ask your 


if you're having difficulties. The page also refers to other solutions.

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