The variables used are:
- A: a dummy variable (1 = bid offer accepted)
- bid: a positive discrete variable (the bid offer)
- income
- du_owner: 1 = house ownership
The script is the following:
list X = income du_owner
...............................
#bootstrapped confidence intervals
genr sel = ok(A bid X)
smpl sel --restrict
store temp.gdt A bid X --overwrite
open temp.gdt --quiet
n = $nobs
list X = dataset - A - bid
loop 5000 --progressive
dataset resample n
#logit regression
logit A const bid X --quiet
#mean and median Willingness-To-Pay
matrix x = {X}
scalar mean_wtp = -($coeff(const)+(meanc(x)*$coeff[3:
$ncoeff]))/$coeff(bid)
scalar median_wtp = -($coeff(const)+(quantile(x,0.5)*$coeff[3:
$ncoeff]))/$coeff(bid)
#printing stats
print mean_wtp median_wtp
#save the coefficients
store wtp.gdt mean_wtp median_wtp
smpl full
endloop
This does not raise any issue, because I managed to remove all the
nested loops.
These loops were in a previous version I deleted, but I replicated the
problem simply adding a (now useless) loop in the new code:
loop 5000 --progressive
dataset resample n
#logit regression
logit A const bid X --quiet
#mean and median Willingness-To-Pay
matrix x = {X}
scalar mean_wtp = - ($coeff(const)+(meanc(x)*$coeff[3:
$ncoeff]))/$coeff(bid)
scalar median_wtp = - ($coeff(const)+(quantile(x,0.5)*$coeff[3:
$ncoeff]))/$coeff(bid)
#USELESS NESTED LOOP....
o = rows(x)
loop for i = 1...o --quiet
series s = 0
endloop
#printing stats on these
print mean_wtp median_wtp
#save the coefficients to file
store wtp.gdt mean_wtp median_wtp
smpl full
endloop
The useless loop causes the program to crash.
Let me know if you need more information or the original db
See you
Giuseppe
On Sun, 2011-01-16 at 09:17 -0500, Allin Cottrell wrote:
> On Sun, 16 Jan 2011, Giuseppe Vittucci wrote:
>
> > I use Gretl 1.9.3 running on Ubuntu 10.04.
> > To calculate some bootstrapped confidence intervals with pairs bootstrap
> > I used the loop in progressive mode and the "dataset resample" command.
> >
> > All works fine if I do not use (simple) loops nested in the first one.
> > When instead I do that, Gretl unexpectedly quits with a "Segmentation
> > fault" error.
>
> It's possible that the problem you've found is fixed in CVS. If
> you could send me a copy of the script you're using I'll run some
> tests. Thanks.
>
> Allin Cottrell
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