I am currently writing up a project I have been working on for a chemistry test.
As part of the testing, I have drawn up a calibration graph on microsoft excel, whereby I enter results from my standards and this produces a calibration curve.
My problem is I need to state when I would accept the graph and when I would not, ie introduce some sort of regression limit or correlation coefficient and state what would be acceptable or not.
I am not statistical minded, but have figured out how to add a correlation coefficient using the formula function on excel based on Pearsons (whoever that is!) However, the result comes out very high ie 0.997, even if I throw a spanner in the works and put a dodgy result in for one of my standards.
If anyone is still reading this and has even a remote idea what I'm talking about, would you have any idea what acceptable linear criteria should be used for acceptance of a graph? So far, they all look good by eye, but I don't have anything set in stone for when it's not.
Many thanks in advance