I have a graph and there are two points that could be two potential outliers. I'm trying to create a polynomial line of best fit with undefined order.
I believe I could use a >2 standard deviations exclusion rule, but I'm sure how exactly this is applied. Do I determine the qualifiying standard deviation by using all the points initially?
That's what I did, but I have two points that qualify for exclusion. Do I remove both at once or one at a time? If I remove only the one with the greatest deviation from the line of best fit, I can recalculate the line and it will give me a new line of best fit of new polynomial order. If this new fit is used, the other point which was previously an outlier is no longer an outlier.
What is the correct procedure?