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: