Recerate the Slope function

**lazyme** · 08-30-2007, 03:55 PM

Thanks for the help in advance.

Simplify the example:

(x,y) intercepts
x = {1,2,3,4,5,6,7,8,9,10}
y = {2,5,8,12,36,48,49,32,22,10}

Assuming these coordinates are in column A and B from row 1 to 10

I used the slop formula to find the slop of all the current values of the slope instead of between each coordinates: slope(B$2:B10,A$2:A10)

my slopes are {3, 3, 3.3, 7.5, 9.34, 9.11, 6.83, 4.65, 2.63}

I also know that the slope formula is:
Sum[ (X-average(x))*(Y-average(y) ] / Sum[ (X-average(X))^2 ]
(for all datapoints)

When I try to recreate the slope formula, I can't seem to be able to get the exact numbers:

calculated slopes {3, 3, 3.32, 7.79, 9.61, 9.26, 6.82, 4.54, 2.47}

Can someone comment or provide some help on how to recreate the slope formula?

Thanks

**Dav** · 08-30-2007, 05:15 PM

Well as writing formulas are not easy i have done it on the attached spreadsheet

The slope formula can be rewritten, check any statistics textbook and is easier to write in excel in this form.

There is a formula by hand for the last value and then the slope column and its equivalent formula next to it

Any clearer

Regards

Dav