Hello,

You probably mean

fit2 <-lm(logDIS~logBMN+I(logBMN^2), data=d)  # d, not dataN


Hope this helps,

Rui Barradas
Em 06-05-2013 00:51, Elaine Kuo escreveu:
Hello all,

I found the following code worked.

code
require(boot)
function.fit2  <-  function(data,i){
           d  <-  data[i,]   #  select  obs.  in  bootstrap  sample
           fit2 <-lm(logDIS~logBMN+I(logBMN^2), data=dataN)
           coefficients(fit2)   #  return  coefficient  vector
           }

boot.fit2  <-  boot(dataN,  function.fit2,  1000)



On Mon, May 6, 2013 at 7:36 AM, Elaine Kuo <elaine.kuo...@gmail.com> wrote:

Hello,

I want to know if two quadratic regressions are significantly different.
I was advised to make the test using
step 1 bootstrapping both quadratic regressions and get their slope
coefficients.
           (Let's call the slope coefficient *â*^1 and *â*^2)
step 2 use the slope difference *â*^1-*â*^2 and bootstrap the slope
coefficent
step 3   find out the sampling distribution above and calculate the % =0
step 4  multiple the % by 2

However, I am new to the package boot.
I wrote a code for step 1 and got a error message.

Please kindly advise how to modify it and thank you.

Elaine

code
require(boot)
function.fit2  <-  function(data){
           #data  <-  data[indices,]   #  select  obs.  in  bootstrap
  sample
           fit2 <-lm(logDIS~logBMN+I(logBMN^2))
           coefficients(fit2)   #  return  coefficient  vector
           }

boot.fit2  <-  boot(dataN,  function.fit2,  1000)

error
fit2.boot  <-  boot(dataN,  fun.fit2,  1000)
Error in statistic(data, original, ...) : unused argument (original)



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