[R] Access to calculations in nls

[Rashid Nassar]

I hope the following helps (and that it is correct!):

> names(summary(fm3DNase1))
[1] "formula"      "residuals"    "sigma"        "df"           
"cov.unscaled"
[6] "correlation"  "parameters"  

> summary(fm3DNase1)$sigma
[1] 0.01919449

> summary(fm3DNase1)$parameters
     Estimate Std. Error  t value     Pr(>|t|)
Asym 2.345179 0.07815378 30.00724 2.164935e-13
xmid 1.483089 0.08135307 18.23027 1.218523e-10
scal 1.041454 0.03227078 32.27237 8.504308e-14

# for the standard errors:

> summary(fm3DNase1)$parameters[,2]
      Asym       xmid       scal 
0.07815378 0.08135307 0.03227078 

Rashid Nassar



On Sat, 14 Oct 2000, Dermot MacSweeney wrote:

> Date: Sat, 14 Oct 2000 19:33:17 +0100 (BST)
> From: Dermot MacSweeney <dsweeney at nmrc.ucc.ie>
> To: r-help at stat.math.ethz.ch
> Subject: [R] Access to calculations in nls
> 
> Hi,
> 
> I would like to be able to access the calculated results from the nls package. 
> Using the example in R, fm3DNase1 we can reurn certain parts of the 
> calculations:
> 
> > coef(fm3DNase1)
>     Asym     xmid     scal 
> 2.345179 1.483089 1.041454 
> 
> > resid(fm3DNase1)
>  [1] -0.0136806237 -0.0126806237  0.0089488569  0.0119488569 -0.0025803222
>  [6]  0.0064196778  0.0026723396 -0.0003276604 -0.0187778127 -0.0237778127
> [11]  0.0381369952  0.0201369952 -0.0335131004 -0.0035131004  0.0150122651
> [16] -0.0049877349
> attr(,"label")
> [1] "Residuals"
> 
> What I would like to be able to return are the Std. Errors shown with the 
> Parameter estimates below. Is there a command such as stderr(fm3DNase1) that 
> would return:
> 
> [1] 0.07815 	0.08135		0.03227
> 
> > summary(fm3DNase1)
> 
> Formula: density ~ Asym/(1 + exp((xmid - log(conc))/scal))
> 
> Parameters:
>      Estimate Std. Error t value Pr(>|t|)    
> Asym  2.34518    0.07815   30.01 2.16e-13 ***
> xmid  1.48309    0.08135   18.23 1.22e-10 ***
> scal  1.04145    0.03227   32.27 8.50e-14 ***
> ---
> Signif. codes:  0  `***'  0.001  `**'  0.01  `*'  0.05  `.'  0.1  ` '  1 
> 
> Residual standard error: 0.01919 on 13 degrees of freedom
> 
> Correlation of Parameter Estimates:
>        Asym   xmid
> xmid 0.9868       
> scal 0.9008 0.9063
> 
> Thanks in Advance,
> 
> Dermot MacSweeney.
> 
> **************************************************************
> 
> Dermot MacSweeney			NMRC, 
> Email: dsweeney at nmrc.ucc.ie		Lee Maltings, 
> Tel: +353 21 904178			Prospect Row, 
> Fax: +353 21 270271			Cork, 
> WWW: http://nmrc.ucc.ie			Ireland
> 
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