求助:我在stata上进行xtlogit固定效应回归,但是模型不收敛,一直不出结果,如下。请问出现这种情况的原因是什么?我尝试删除了一些异常值,但仍旧不收敛。
. xtlogit Zombie Subsidy Market FeeR Holding Size Lev lage q SOE, fe
note: multiple positive outcomes within groups encountered.
note: 1,522 groups (15,199 obs) dropped because of all positive or
all negative outcomes.
note: Market omitted because of no within-group variance.
note: lage omitted because of no within-group variance.
note: SOE omitted because of no within-group variance.
Iteration 0: log likelihood = -2.3025851
Iteration 1: log likelihood = -3.553e-15 (not concave)
Iteration 2: log likelihood = 3.553e-15 (not concave)
Iteration 3: log likelihood = 3.553e-15 (not concave)
Iteration 4: log likelihood = 1.066e-14 (not concave)
Iteration 5: log likelihood = 1.066e-14 (not concave)
Iteration 6: log likelihood = 1.066e-14 (not concave)
Iteration 7: log likelihood = 1.066e-14 (not concave)
Iteration 8: log likelihood = 1.066e-14 (not concave)
......