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2011 November 18

Titles for graphs

Filed under: Uncategorized — gasstationwithoutpumps @ 00:25
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An AP Bio teacher on the ap-bio mailing list wrote

I keep finding that the some AP students do not know how to write a proper title for graphs. I tell them that a title basically describes the information that is being presented. They give one- or two-worded titles which I believe is not sufficient enough. 

  1. Does anyone have a suggestion on how to show the AP students how to title their graphs correctly?
  2. Is it okay for them to use “vs.” in a title? An example title: Light intensity vs. depth

The problem is not limited to AP students.  I find that grad students, postdocs, and faculty often have no idea how to label a graph.  The journal literature is full of badly labeled graphs.

I don’t like “light intensity vs. depth” as the title of a graph.

First, the axes should already be labeled (“light intensity (lux)” on the y-axis and “depth (cm)” on the x-axis), so the title adds no information—in fact, it tempts people to omit the more important axis labels.

Second, about 20% of students get the convention reversed for “versus”, doing “x vs. y” instead of the standard “y vs. x”.

Third, what are you measuring light intensity of?  I can’t think of a biology experiment where that is the right thing to plot.  Either you should be plotting luminous flux (in lumens) for something emitting light or absorbance (the more common measurement in bio labs). You might measure lux—that is what a light meter usually measures, but that measurement depends on the distance and size of the sensor, so should be converted to lumens for the  source before plotting, or absorbance of the suspension, depending on what the underlying phenomenon being measured is.

It would be better to give a descriptive title: “Bioluminence is highest at the surface”.  The worst titles are ones that convey no information, like “Results” or “Measurements”.  I hate meaningless section titles also. The style that makes every paper have an identical outline with identical section headers is one I abhor, as it minimizes the information presented to the reader.

If you are doing formal write-ups (rare in AP bio or freshman college classes, but common at the grad level), every figure or table should have a paragraph-long caption, not just a title.  The reasoning is that most readers of a journal article only read the abstract and look at the pictures, and so the figures and captions have to convey the main ideas of the paper. Even those who do read the full paper generally thumb through and look at the pictures first.  The figures and captions should amount to a poster presentation of the whole paper—if the figures are mysterious, the paper never gets read, and the writing of it was wasted.

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3 Comments »

  1. This is an interesting question and answer. May I forward it to a teacher at my daughter’s high school? Thanks for sharing!

    Comment by Tamara Lichtenstein — 2011 November 18 @ 07:21 | Reply

    • I would love to have you forward the URL for the page—the blog is publicly readable. I’d rather people did not copy my writing, though, both because it offends me as scholar to have unattributed text floating around, and because I hate getting attachments in e-mail for stuff that is publicly accessible by the web. I want people to get in the habit of e-mailing links, not documents, whenever possible.

      Comment by gasstationwithoutpumps — 2011 November 18 @ 09:10 | Reply

  2. Declarative titles ALWAYS, in graphs in Figures, on slides, etc. Tell them what you think the data means–thanks for pointing this out.

    Comment by Mark Peifer — 2011 November 21 @ 12:39 | Reply


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