Gompertz curve

[salvomic]

(03-31-2015 01:54 PM)Marcio Wrote:  The correct values for A, B and C are 1.151, 0.5191 and 0.1509 respectively. For those, R^2 = 0.9916.

thank you. You're right: so the two curves are more close with the range of our data

Quote:Let me know if you still need the program. I will have to edit it to make it more user-friendly.

you're very kind.
Yes, I would like to try it.
We could also make a program with mine and yours functions to treat Gompertz Curve...

Quote:And yes, the curves are indeed very similar but only for that region your data covers, outside of that area the functions behave differently, that means that the estimates you found for A, B and C using the logistic fit might not be the best for extrapolation.

Marcio

yes, indeed.
With those data I can see (in Statistic 2var) they are however enough close also for extrapolation, but generally speaking above the range there is a difference and with Gompertz often the purpose is to predict future values...
In our case Gompertz seems to be below Logistic in the left tail and over it beyond the range of the Y...

However in this case Logistic is always a good approximation.

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In the image the two curves (orange Gompertz, green Logistic) in Statistics 2var