Wikipedia:Reference desk/Archives/Mathematics/2014 July 8

= July 8 =

How does this graph work? How is it possible?
This is the weirdest real-life graph I've ever seen: []

Source:

IMF Staff Discussions Note: Emerging Markets in Transition: Growth Prospects and challenges.

(bottom of page 4) — Preceding unsigned comment added by 14.200.130.252 (talk) 11:32, 8 July 2014 (UTC)


 * Graphical representations of parametric equations often look like that. Dolphin  ( t ) 12:22, 8 July 2014 (UTC)


 * Thank you for that. It did help shed a bit of light and introduced me to paramtric vs non-parametric equations :) I guess there wasn't a proper function in this graph, it was just simply data points plotted and therefore the line we see in the graph is a bit misleading because we could join the 'dots' in any way we like. 14.200.130.252 (talk) 14:22, 8 July 2014 (UTC)
 * The dots are joined in chronological order. You can see the years marked next to each location in the graph. -- Meni Rosenfeld (talk) 15:45, 8 July 2014 (UTC)


 * That graph doesn't seem to show a case where one axis variable is strongly dependent on the other, which is what is most familiar (for example, population is strongly dependent on time). If you plot two largely independent values, the graph will take on a rather random look (for example, sound volume versus frequency in a piece of music).  Such graphs seem less useful, to me.  I'm not sure how you are supposed to use it to predict anything. StuRat (talk) 14:30, 8 July 2014 (UTC)


 * Such a graph can help you see whether the variables are independent. —Tamfang (talk) 04:52, 9 July 2014 (UTC)


 * Agreed, that's the only point I see in it. StuRat (talk) 15:11, 13 July 2014 (UTC)


 * It isn't intended to predict anything; it simply provides an easily read display of how the two variables related to each other at different times. It's no different in principle than plotting the path followed by a vehicle or a person over time, like this map or this map... except that with a map, latitude and longitude are obviously related, whereas with a graph showing two functions over time, their relationship may not be obvious.  — Preceding unsigned comment added by 50.100.189.160 (talk) 06:22, 9 July 2014 (UTC)


 * Right, but just what is the point in showing how two apparently unrelated variables change relative to one another over time ? I could plot the rabbit population against the stock market indices, too, but why would I ? StuRat (talk) 15:11, 13 July 2014 (UTC)