如题，目前所使用的是截面数据，在使用mvtobit命令估计三个被解释变量的tobit模型时，一直显示迭代，not concave的情况；而当只是用两个被解释变量估计tobit模型时，就可以得出很不错的结果，请问能够怎样才能成功得到三变量tobit模型？已经尝试用过剔除异常值、删减变量等方法，希望有老师可以讨论或者解答一下，不胜感激
mvtobit (ln_net_asset = ln_fincome1_per fml2016_count pchild pold cfps_age cfps_age2 cfps_gender future believe health account marriage edu party employ work )
(ln_total_asset = ln_fincome1_per fml2016_count pchild pold cfps_age cfps_age2 cfps_gender future believe health account marriage edu party employ work )
(ln_total_debt = ln_fincome1_per fml2016_count pchild pold cfps_age cfps_age2 cfps_gender future believe health account marriage edu party employ work )
这是目前的命令