Re: Curve-fitting/data analysis question...

*To*: mathgroup at smc.vnet.net*Subject*: [mg73359] Re: Curve-fitting/data analysis question...*From*: "Robert Dodier" <robert.dodier at gmail.com>*Date*: Wed, 14 Feb 2007 05:14:59 -0500 (EST)*References*: <200702110615.BAA11578@smc.vnet.net><eqsa48$jn0$1@smc.vnet.net>

sherifffruitfly wrote: > For each point p in my interval, I constructed two models - a linear > one using the points to the LEFT of p, and an exponential one using > the points to the RIGHT of p. I ran chi-squared to see which model p > belongs to. At the beginning, LEFT wins pretty much every time. When > RIGHT started winning is where I called the cut-off. Better still would be to choose the cut-off point to minimize the sum of the goodness of fit (i.e., chi-square) on both sides. (It's not a question of which side fits better, but rather how to get better fit overall.) Maybe you're already doing that; I can't tell for sure. I would be interested to hear whether the total chi-square is sensitive to the placement of the cut-off point. Do you find that there is one point which is much better than the rest, or is there a range of points which are all more or less OK? HTH Robert Dodier

**References**:**Curve-fitting/data analysis question...***From:*"sherifffruitfly" <sherifffruitfly@gmail.com>