Notice: On April 23, 2014, Statalist moved from an email list to a forum, based at statalist.org.
[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: st: RE: inflection point of sigmoid curves
From
Austin Nichols <[email protected]>
To
[email protected]
Subject
Re: st: RE: inflection point of sigmoid curves
Date
Mon, 14 Jun 2010 17:17:15 -0400
Johannes Schmid--
Try these silly examples:
drawnorm x, mean(10) n(1000) clear
sort x
g y=(_n+1)/(_N+2)
reg x c.y##c.y##c.y
loc ybar=-2*_b[c.y#c.y]/(6*_b[c.y#c.y#c.y])
set obs `=_N+1'
replace y=`ybar' in l
ipolate x y, gen(px)
loc xbar=px[_N]
lpoly y x, nosc xli(`xbar')
webuse nhanes2, clear
ren bpsystol y
ren age x
reg x c.y##c.y##c.y
loc ybar=-2*_b[c.y#c.y]/(6*_b[c.y#c.y#c.y])
set obs `=_N+1'
replace y=`ybar' in l
ipolate x y, gen(px)
loc xbar=px[_N]
lpoly y x, nosc xli(`xbar')
On Mon, Jun 14, 2010 at 3:12 PM, Nick Cox <[email protected]> wrote:
> I am not aware of a unique recipe for sigmoid curves. But in general fit
> a suitable function, apply calculus and plug in suitable parameter
> values.
>
> Nick
> [email protected]
>
> Johannes Schmid
>
> Is it possible to calculate the inflection point in sigmoid curves in
> STATA,
> and how can it be done?
*
* For searches and help try:
* http://www.stata.com/help.cgi?search
* http://www.stata.com/support/statalist/faq
* http://www.ats.ucla.edu/stat/stata/