[R] Fitting a logistic regression

[1Rnwb]

with my limited understanding, I am not surprised to see this data fitting
nicely at the end just by eyeballing at it. the reaction at the early time
point is not completed as the time passes which is close to 20 units the
reaction generates more metabolite to be measured reliably your t=0 and t=10
are basically the same, if i limit the digits to 2 then the values will be
0.20. you can do the log transform and then try to fit it.


Dani Valverde-4 wrote:
> 
> Hello,
> I have this data:
>   Time  AMP
>      0 0.2000000
>     10 0.1958350
>     20 0.2914560
>     40 0.6763628
>     60 0.8494534
>     90 0.9874526
>    120 1.0477692
> 
> where AMP is the concentration of this metabolite with time. If you plot
> the data, you can see that it could be fitted using a logistic
> regression. For this purpose, I used this code:
> 
> AMP.nls <- nls(AMP~SSlogis(Time,Asym, xmid, scal), data =
> concentrations,model=T)
> 
> When plotting the fitted function, it seems that it fits quite well at
> the end of the time. However, at the beginning it seems that the fit is
> not so good. How can I achieve a better fit? Forgive me if it is a
> stupid question, but I am just starting with non linear regression.
> Thank you,
> 
> Dani
> -- 
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> 
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