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Excel Slope function disagreement with 'longhand' results

aasikolo
aasikolo asked
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Good Afternoon,

I have beeen working on a linear regression problem, and one of the issues at hand, is whether to throw out certain outliers, if you will, from the dataset.  To do so, it seemed reasonable to examine the effect on the slope of the line, by progressively including values to the dataset, since the 'outliers' are at teh upper end of the results, and observing the effect on the slope and r squared values. Just out of curiosity, I entered the formula Excel uses for calculating the slope in 'longhand' for comparison purposes and observed differences between the longhand method and the slope function results.  Please see columns H and J in the attached file.

It will be interesting to see what I am missing this time, besides the bus.

Thanks again,

aasikolo Slope-Test.xls
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Commented:
You are using a fixed mean for all the cases. The mean should vary for each line.
byundtMechanical Engineer
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Commented:
See sample spreadsheet using the approach ssaqibh is describing. It agrees with SLOPE function very well.
Slope-TestQ27426585.xls

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Commented:
Don't I feel silly

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