Regression slope doesn't match the slope / linest formula! Help!!

[vtanuku]

I am calculating the slope for a set of sales data over a 2 year period through Linest / slope function and charted it out as well...the equation on my regression line (the "m" value) is way different than the slope i calculated using the formula. Can any one help me on this? what am I doing wrong? or is there any caveats to the formula / chart?

Thanks,
VT

 

[pgc01]

Hi vtanuku
Welcome to the board

You don't post any data so it's difficult to guess what's happening.

Please post the data, the formula you used and the m values you got.

If it is too much data, post a working example with a small sample where you have the same problem.

 

[vtanuku]

Thanks PGC01 for the reply. I will make sure I post the data next time onwards. The data I had was something like this:

Column A column B (sales)
1/2007 2213
2/2007 1335
3/2007 2552
and so on...

I figured this out myself. seems like the slope formula doesn't work (or rather gives a different slope!!!) if I have months as it is (I had monthly sales as my x variable) as one of the variables, but has to be numerals (1,2,3..) to match the slope on the chart (linear trend line).

Instead of using the above two columns, I had to use columnB (sales) and one another variable which is just 1,2,3.....

Rgrds,
VT