A graph with 3 sets of units ??

sudzs · 17-01-2014 12:28PM #1

I'm stumped here trying to plot a line graph that has time/weeks along the x axis and then I have units/ml, ng/ml and ug/ml for the y axis. I could manage 2 units on 2 y axis, one on the left, one on the right, but how to get a third in??

I'm probably missing something blindingly obvious but have been searching online for ages and my brain is frazzled!

Edit: Ok, I thinkI figured out what to do... just put another axis for ng/ml beside the ug/ml one and put the units/ml on the other side. Would that be right?

Yakuza · 17-01-2014 01:35PM

Are you graphing several different y variables with respect to one x-variable?
These links might be useful:
http://peltiertech.com/Excel/ChartsHowTo/PanelUnevenScales.html
http://peltiertech.com/Excel/Charts/TertiaryAxis.html

Personally, I'd find 3 Y-axes confusing and unclear. Can you scale one of the sets of data to fit into one or other of the axes?

sudzs · 17-01-2014 02:26PM

Yakuza wrote: »

Are you graphing several different y variables with respect to one x-variable?

Yes, that's it exactly. One x and three y variables

Can you scale one of the sets of data to fit into one or other of the axes?

I thought of that but I would have a range or from 0.50 ng/ml to 950 ng/ml ! I'd need a very big piece of graph paper!!

Thanks for the links, I'll check them out. And glad I'm not the only one confused by it all. It's part of an assessment i have to do so maybe it's a test!!

Mucco · 17-01-2014 10:17PM

Do a log scale on the y-axis:
1, 10, 100, 1000 etc....
very common, Excel has an option for it, you can also choose a secondary axis.

sudzs · 18-01-2014 09:55AM

Mucco wrote: »

Do a log scale on the y-axis:
1, 10, 100, 1000 etc....
very common, Excel has an option for it, you can also choose a secondary axis.

Thanks Mucco, It has to be hand drawn it so went for putting in another y axis.

A graph with 3 sets of units ??

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