This answer quotes ChatGPT
This warning message means that the coefficient of at least one independent variable may become infinite when Cox regression analysis is performed. This usually occurs when the sample data has problems such as complete separation or collinearity.
Because in Cox regression, the coefficient of the independent variable represents the risk ratio that affects the survival time, and an infinite coefficient will lead to the unreliability of the model. Therefore, this problem needs to be dealt with.
First, you need to check the unique value and frequency of each argument to see if there is a complete separation. If there is a complete separation, consider merging the relevant arguments or using the exact method of analysis. If you don't have complete separation, then you can consider using regularization methods such as Lasso or Ridge regression to reduce the number of arguments and prevent collinearity problems.
In addition, you can try to remove outliers from the data set or solve the problem by increasing the sample size.
In summary, the data sets and models need to be carefully examined to find the cause of the problem and take appropriate measures to deal with it.
