Dear Experts,

I am doing a DCE study and use the command of mixlogitwtp to estimate WTP space. All my qualitative attributed are effect coded. I know that if I estimate WTP via the traditional method that calculates the ratio of the negative coefficient of the non- monetary attribute to the coefficient of the monetary one, I should multiply the ratio by 2 to get WTP if using effect code. Then how to calculate WTP space using effect code and estimating via the command of mixlogitwtp? Here is the result of mixlogitwtp.

. mixlogitwtp choice, group(k) price(mpremium) id(id) rand(rela pay item1 item2 item3 gov)

Iteration 0: log likelihood = -4967.1614 (not concave)
Iteration 1: log likelihood = -4966.7308 (not concave)
Iteration 2: log likelihood = -4937.9077 (not concave)
Iteration 3: log likelihood = -4705.6884
Iteration 4: log likelihood = -4645.5122
Iteration 5: log likelihood = -4611.9929
Iteration 6: log likelihood = -4611.2852
Iteration 7: log likelihood = -4610.3387
Iteration 8: log likelihood = -4610.3347
Iteration 9: log likelihood = -4610.3347

Mixed logit model in WTP space Number of obs = 19,206
Wald chi2(7) = 49311.95
Log likelihood = -4610.3347 Prob > chi2 = 0.0000

------------------------------------------------------------------------------
choice | Coef. Std. Err. z P>|z| [95% Conf. Interval]
-------------+----------------------------------------------------------------
Mean |
rela | 603.4376 114.4839 5.27 0.000 379.0532 827.8219
pay | 1.046292 .1794451 5.83 0.000 .6945861 1.397998
item1 | 219.5909 76.70401 2.86 0.004 69.25382 369.928
item2 | 161.464 72.78486 2.22 0.027 18.80827 304.1197
item3 | 95.26531 60.61126 1.57 0.116 -23.53057 214.0612
gov | 21.67747 3.672156 5.90 0.000 14.48018 28.87477
mpremium | -7.260442 .1834876 -39.57 0.000 -7.620071 -6.900813
-------------+----------------------------------------------------------------
SD |
rela | -1220.918 219.1544 -5.57 0.000 -1650.452 -791.3828
pay | -.3324351 .0738233 -4.50 0.000 -.4771261 -.1877441
item1 | 1003.145 191.0772 5.25 0.000 628.6406 1377.65
item2 | 725.3507 157.9364 4.59 0.000 415.801 1034.9
item3 | 427.8107 150.9915 2.83 0.005 131.8728 723.7486
gov | 12.88839 3.633659 3.55 0.000 5.766551 20.01023
mpremium | .0599947 .0903408 0.66 0.507 -.1170699 .2370594
------------------------------------------------------------------------------
The sign of the estimated standard deviations is irrelevant: interpret them as
being positive