Is it possible to create a hyperbolic best fit line, rather than using only
the options for type of trendline that excel has? If so, how would I do it?

Hi Ed,

You can use the 'Solver' Add-in in Excel to fit any user-defined
function to {x,y} data. If the add-in is not already installed, go to
'Tools' -- 'Add-ins' -- select 'Solver Add-in'; Excel might require the
Excel or Office CD for installing the add-in. Once installed, the add-in can
be accessed by clicking 'Tools'.

Let's say you have your xdata and ydata in columns A and B. Create a
column (say Column C) for calculated y values (let's call them ycal) using
the hyperbolic function you want to fit to the data by invoking x values from
the xdata column, and the parameters for the function placed in some cells
(you have to enter some reasonable initial guess values for those parameters
- 1 might work). Now create another column (say Column D) which is
(ycal-ydata)^2. Place the sum of Column D in a cell (let us call that SSR)

Now invoke Solver (in Tools); the solver window pops up. Enter the
cell address for SSR in 'Target Cell', select the 'Minimize'-button, enter
the cell addresses of the parameters in 'By changing' bar, and click 'Solve'.
If everything goes well, the parameter cells should update to show optimized
values of the parameters. You can superimpose a plot of ycal vs xdata on a
plot of ydata vs xdata, to see the quality of the fit.

Sorry that my reply is looong and maybe confusing.

Regards,
B.R. Ramachandran

"ed" wrote:

Is it possible to create a hyperbolic best fit line, rather than using only
the options for type of trendline that excel has? If so, how would I do it?