张老师我在用spss做多值logit回归分析时出现以下警告
Warnings
Unexpected singularities in the Hessian matrix are encountered. This indicates that either some predictor variables should be excluded or some categories should be merged.
The NOMREG procedure continues despite the above warning(s). Subsequent results shown are based on the last iteration. Validity of the model fit is uncertain.
请问代表什么意思啊？另外在做多值logit回归分析时 对原始数据有什么要求吗？