[R] Need to replicate Boltzman Signmodial Curve fit from Graph Pad

[Bert Gunter]

I think you'll find that this is just an alternate parameterization of
a 4 P logistic.
... and in any case there is no statistically detectable difference
between the two.

That is, this is just basically a Graphpad marketing ploy. Fit such
data with anyone's logistic function ... and that is probably
overfitting in many cases, anyway.

Cheers,
Bert

On Tue, Apr 23, 2013 at 9:54 AM, John Kane <jrkrideau at inbox.com> wrote:
> No idea of the area but does this link help? http://bioinformatics.oxfordjournals.org/content/24/13/1549.full
>
> John Kane
> Kingston ON Canada
>
>
>> -----Original Message-----
>> From: rnoobier at gmail.com
>> Sent: Tue, 23 Apr 2013 10:55:59 -0400
>> To: r-help at r-project.org
>> Subject: [R] Need to replicate Boltzman Signmodial Curve fit from Graph
>> Pad
>>
>> Hello useRs (please don't kill me),
>>
>> I've fairly new to R having only a few months of playing around with R.
>> What little I've learned has been extremely useful.
>>
>> If someone could point me as to how to replicate the Boltzman Sigmodial
>> curve fit as provided by Graphpad software I'd be eternally grateful.
>>
>> Where  we currently use Graphpad for only this one function,its seems
>> highly inefficient for a $100 piece of software to be used for only one
>> function (which isn't nearly as bad as the company's pandemic reliance on
>> Excel for nearly everything else).
>>
>> so anyway, what I'd normally do is take a set of data like this:
>>
>>  pH counts  3.8 968  5.0 1347  5.8 2867  6.6 9203  7.0 15817  7.4 20297
>> 8.2
>> 31916  9.2 35756
>> then fit this to a Boltzman sigmodial in Graphpad. Graphpad spits out a
>> much longer set of vectors and also information about v50 and confidence
>> intervals etc (if anyone is familiar with that software). This is what
>> i'd
>> like to replicate.
>>
>> It might be that I just don't know what i'm doing,so feel free to call me
>> an idiot but any help is greatly appreciated!
>>
>> -JJ
>>
>>       [[alternative HTML version deleted]]
>>
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>
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-- 

Bert Gunter
Genentech Nonclinical Biostatistics

Internal Contact Info:
Phone: 467-7374
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