Trend Analysis with excel

[genichigo]

Hi Guys, im trying to work out a few trend lines in excel so i can start to predict data in the future.

Im trying to work out the Logarithmic, Exponential, Power, linear and Polynomial trend lines, I Know the math behind them, but im not sure how to get excel to calculate it,
anyone with knowledge on this?

[TMS]

Think you need to talk to Andy Pope. Or start by looking at his web site: http://www.andypope.info/charts.htm


Regards, TMS

[MrShorty]

Can you be more specific in your question? Are you having trouble getting Excel to perform the regression, or are you having trouble using the results of the regression, or something else?

TMShucks has assumed you are using the chart trendline feature to do the regression. I personally prefer to use the LINEST() worksheet function to perform these regressions. Note that the "linear" in LINEST() refers to linear functions as you would learn them in a linear algebra course, so it refers to much more than straight lines. Each of those equation types mentioned can be expressed as a "linear" function. My approach to this looks like this:

1) Enter raw data into spreadsheet.
2) Build the regression matrix for the equation form I want to use. In some cases, the raw data table will work, others will require a completely new table built off of the raw data.
3) Use LINEST() to perform the regression and return the parameters for the equation
4) Then use the equation with the regressed parameters to calculate y and known x or x at known y depending on needs.

If you need further help, a more specific question will likely generate a more specific response.