I am looking for methods to calculate the error in a slope. the caveat is that my values themselves are averages with a STDEV. E.g. x 1+-1% 2+-1% 3+-1% y 0.14+-0.01 0.27+-0.02 0.42+-0.02 (using http://www.cartage.org.lb/en/themes/sciences/chemistry/Miscellenous/Helpfile/Erroranalysis/MultiplicationDivision/MultiplicationDivision.htm [Broken] as the calculation method for these errors) This could be simplified by assuming the x-values have no deviation. Now I can just plot the average slope of those three values, I can make a simple linear regression analysis, obtain the least square values as shown here https://www.physicsforums.com/showthread.php?t=194616 and somewhat related here https://www.physicsforums.com/showthread.php?t=173827 or use the Excel Linestatistics (http://www.trentu.ca/academic/physics/linestdemo.html) I obtain a value for the slope of my averaged slope, and a STDEV, based on the Least Square algorithm. But this does not take into account at all my initial STDEV. Is there a more general algorithm that can take STDEVs in the initial (at least) y values, or both x and y values, and how would I calculate that? Thank you.