- #1

- 67

- 1

## Main Question or Discussion Point

Hello! I have a fit to a histogram ##y(x)##. Now I want to predict the number of counts at some other point, not in the original data, using this fitted function and assign an error to it. Let's say that the the point where I want to compute this value, ##x_0## gives ##y(x_0) = 100##. As the function ##y(x)## was obtained from a fit, it has some error associated to the error propagation of the errors on the parameters of ##y##. Let's assume that that error is 2. Now, as this functions measure counts, the error associated to it can be considered a Poisson error i.e. assuming that I wouldn't have that error of 2, I would give my result as ##100 \pm \sqrt{10} = 100 \pm 10##. Now given that I have that 2, can I just add the two sources of error in quadrature and give my result as ##100 \pm \sqrt{4+100} = 100 \pm 10.2##? Is this correct?