Hi, so basically I'm having trouble getting a straight answer with this: how do we find the uncertainty in a gradient using the worst lines (i.e lines passing through the error bars giving the greatest and least possible gradients). I've read in the textbook (cgp) that the uncertainty is simply the range of the worst gradients. However, on the markscheme for last years paper 3 section A, the correct method was to find the range and half it. And to make it more confusing another markscheme says it is just the range. So which is right? Range or range/2?