Ratio vs Average rather than Difference

[jameshunterbr]

I am working on a project for which I need a Bland-Altman graph and table that relies on the ratio between the two measurements rather than the simple difference. I didn't see how I could do that with the current form of the package. It's fairly straightforward to include in the blandr.statistics list an item for ratio in the form of the first variable over the second. Then, the blandr.draw and the blandr.output.text functions could have parameters that would call the ratio for the y axis instead of the difference.

Overall, I think you can improve the functioning of the package for biologists and medical folks out there by making blandr.statistics a required step. The user could put all the parameters they desire (e.g., ratio = TRUE) in that call and the draw and output.text functions could then read them from the blandr.statistics output list.

I would be willing to help you with the first of these points (adding the ratio option), but not for about 3 months until a number of new projects in our lab settle down.

I like what you have done with this and it's certainly useful for us in biology and medicine. So, thanks!