This is an essay. It contains the advice or opinions of one or more Wikipedia contributors. This page is not an encyclopedia article or a Wikipedia policy, as it has not been reviewed by the community.

The page Wikipedia:How to create graphs for Wikipedia articles gives some technical information about how to create graphs for Wikipedia (in particular, which programs and format to use). This text also deals about how to create graphs, but in the sense of what to plot.

I started writing this page a while ago, but just copied it here after seeing Image talk:Mauna Loa Carbon Dioxide-en.svg and the related page Wikipedia:Don't draw misleading graphs. I am glad to see that someone else is interested in this topic, and I hope it'll motivate me to add more content (to this page or the page mentioned earlier).

Do not expect too much from it since,at the moment, it is only a list of ideas and references.

One recurrent and controversial question is whether a graph should show the baseline (that is, most of the time, the value 0). According to Darrell Huff ^[1], it should, but Edward Tufte disagrees.^[2]

This question is often translated into "should my graph include 0 ?", but it is important to realise that what is called "0" on a certain scale may be just arbitrary. For example, temperatures are most often measured according to one of three scales: Kelvin, Celsius and Fahrenheit (see Temperature measurement#Comparison of temperature scales for examples of some other scales), and the three of them use different reference point (different "0"s).

If someone wants to graph human body temperatures, for example, none of these 0s has any interest (indeed, at degrees on any of these scales correspond to someone who is dead !)