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>> > You're welcome. > > By the way, I also noticed that you wanted to add a vertical line where > your plot crossed zero. That's a slightly deeper question, as The OOo > plot is using straight lines to join the points, and the estimated zero > point would probably lie on a fitted curve. > > If you do need to do that, you would probably need to use a linear model > in a package like R, and then add the line based on the estimated zero > point. Looking at your data it could be modelled by a quadratic (e.g. y > ~ f[x, x^2]). You would, of course, fit the curve to all the data, > rather than the averages for each molarity. I'd never heard of R before today, but I'll definately take a look at it. I'll be studying Nursing for the next three years at uni, during the first year I'll still be doing the biology so may need it. > > Otherwise you could estimate the zero point by "eye-balling" it. In order to get the work done that's pretty much what I did, I used a vertical rule in a drawing program to add the line and a blob at the point. I've attached the final thing if anyone wants a look.
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