请问，因变量某类人数太少（分类不能合并），多分类logistic回归最后的结果发现OR值特别大，且结果明显是错误的，是不是说明不适合用logistic回归？
运行结果出现了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. 似乎说明有多重共线性或需要合并种类？这是否说明不适合用logistic回归？