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I have some data which concists of some points (x,y) and I'm looking for a program that can calculate for me the slope of the linear fit line (trendline) including uncertanity on the slope. Also the y-interception has to bo at 0.

My data set includes incertanities on both x and y variables.

I have tried this in excel. I can get the slope for the line that has y-intercept = 0, and I can add in the graph my uncertanities, but I cant find out how to calculate the uncertanity of the slope.

I tried another program called graphical analysis. That program can easily give me the slope and the uncertanity of the slope. But I can't seem to find out how to force y-intercept to 0 (force the line through the point (0,0) )

So my questions in general are:

Is there another program that is better suited for this?

How can I calculate uncertanity for the trendline in Excel?

How can I force the trendline (linear fit line) to go through the point (0,0) in Graphical Analysis.

An answer to just one of these questions would be sufficent :)

best regards

frímann kjerúlf

student of University of Iceland