
1. Re: Export Exact Trend Line Formula?
Dmitry Chirkov Aug 2, 2016 11:38 PM (in response to Benjamin Greene)We currently don't expose exact numbers used in these sort of calculations, sorry! (plus formatting is inconsistent between tooltip and Describe Trend Line dialog)
Curious though  why do you have a need to replicate this formula?

2. Re: Export Exact Trend Line Formula?
Benjamin Greene Aug 3, 2016 7:50 AM (in response to Dmitry Chirkov)I am working with crosssectional data, so I was trying to see how someone's probability of Y occurring changes, given their value for X. So I fit a trend line using all the observations that I have both X and Y values for and was hoping to apply that trend line to those observations that I only have X values for, to get a predicted Y value. However, as you can see in the packaged workbook, the predicted values aren't coming out quite right.
I ended up just using Excel's LINEST array formula to obtain exact coefficient values.

3. Re: Export Exact Trend Line Formula?
Carl Slifer Aug 3, 2016 8:05 AM (in response to Benjamin Greene)Hi Benjamin,
You're right it's a significant difference on a graph and its not a simple transformation. I'm not the most skilled R programmer in the world in fact probably barely even considered an R anything. But this might be a case to link Tableau to R and to pull the calculated trend line data off from it, especially something as large and complicated as a 5th degree polynomial trendline to calculate. Have you looked into this route?
Best Regards,
Carl Slifer