exponential regression

*To*: mathgroup at smc.vnet.net*Subject*: [mg129655] exponential regression*From*: r.aufmann at gmail.com*Date*: Sun, 3 Feb 2013 02:45:43 -0500 (EST)*Delivered-to*: l-mathgroup@mail-archive0.wolfram.com*Delivered-to*: l-mathgroup@wolfram.com*Delivered-to*: mathgroup-newout@smc.vnet.net*Delivered-to*: mathgroup-newsend@smc.vnet.net

I entered Clear[a, b, x]; FindFit[{{1, 4.5}, {3, 14.0}, {5, 28.6}, {7, 54.1}, {8, 78.6}}, a*b^x, {a, b}, x] as a text of exponential regression. The input returned {a->4.66625, b->1.42272} Fine. However, a student of mine entered the same data in a TI-84 calculator and it returned 3.947506 (x^1.334589). These two equations are obviously not the same. Does anyone know why there is a discrepancy? By the way, I tested a data set that is exactly exponential. FindFit and the TI-84 returned exactly the same equation. Thanks for any insight.

**Follow-Ups**:**Re: exponential regression***From:*Bob Hanlon <hanlonr357@gmail.com>