Skip to main content

Modeling Plug-in Suggestion

2 posts / 0 new
Last post
WBY
WBY's picture
Modeling Plug-in Suggestion

When fitting polynomials to light curves you generally avoid over-fitted polynomials that exhibit "wiggles" near the ends of the data set that are not supported by the trend of the data. However, currently in VStar, we have no way of avoiding polynomials that "fly-off" in unrealistically  before the data set begins or after it ends. here is an example from the Analyzing Data with VStar course. The 6th order polynomial is the best fit to the data according to the AIC and BIC criteria for polynomial orders 1 through 10. If you plot the data with an extrapolation of the 6th order model beyond the ends of the data, you see the following. 

By the way this is data of monthly  atmospheric CO2  measurements. I think it would be helpful to have a plug-in that would plot the data and the model over a time period having a user selectable extension beyond the ends of the data. Having such a view 

 

PS: I originally uploaded the wrong order fit.  This is the correct one but it is still completely unrealistic. 

David Benn
David Benn's picture
Modeling Plug-in Suggestion

Hi Brad

When you say the following:

...a user selectable extension beyond the ends of the data...

do you have in mind the ability to create a model that is essentially a piecewise function defined so that times before and after the end of a "sane" fit time range such as you show for the Mauna Loa CO2 data above can be treated independently?

David

Log in to post comments
AAVSO 49 Bay State Rd. Cambridge, MA 02138 aavso@aavso.org 617-354-0484