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hi
is it possible to use the trendline equation to calculate the numerical values? So basically using it to forecast actual data instead of just a trend line?
Many thanks for any help
hi
is it possible to use the trendline equation to calculate the numerical values? So basically using it to forecast actual data instead of just a trend line?
Many thanks for any help
Hi,
Yes it is. You need only replace the X in the formula with the relevant cell references that contain the X values you wish to use.
Don
Please remember to mark your thread 'Solved' when appropriate.
hi thanks for reply
not really sure about that
this is formula y = 1.7458e-0.121x
or Rē = 0.9303
my x axis is weeks so would i put the week number into the formula?
It would depend on what values are currently feeding the chart. You should match those- I usually put the formula in a column alongside the actual values so that I can see actual versus trend for each point. If you are having problems, a sample file would allow me to show you. You can also calculate the two coefficients directly.
would you mind looking at the sheet? the trend is underneath the table
Thanks
See link for example. Post#6 has attachment using LINEST to obtain slope & intercept (for linear regression).
http://www.excelforum.com/excel-gene...d-formula.html
For polynomial regression. You can see example in link below (example is for 2nd order polynomial) and is solving for x. But you can easily adopt for larger order polynomial and to solve for y (no need for solver to solve for y).
See Post#2.
http://www.excelforum.com/excel-gene...d-formula.html
Thank you
Does it work with exponential?
For exponential formula. Using your example...
=1.7242*EXP(-0.119*X)
Replace X with cell reference to where x value is stored.
For how to use LINEST to fit non-linear curve... see link.
https://newtonexcelbach.wordpress.co...curve-fitting/
Your chart X values are text, so they are actually being treated as 1,2,3,4 etc. Also, to calculate the coefficients we need to exclude the blank values. I've added two new columns to the left with these calculations in, and the two blue cells below the chart are the ones that calculate the coefficients.
Awesome thank you!
If i want to create the trend, using say the previous 3 weeks data, can i adjust the formula to select that last 3 weeks data?
Thanks
You'll need to make sure the column A values start at 1 for the first data point.
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