I am new to R and and random regression forest. Right now I am working with a dataset of 60 input variables (dummy variables and continuous variables) and try to find the most important variables, which describe my dependent variable best. Therefore I am using the permutation-based OOB-MSE.
My problem is now, that each time I run the random forest, the ranking of the variables changes even when I just repeat the command with the same amount of ntree and mtry. First I was thinking that it had something to do with the randomized number of variables used in each tree, so I increased ntree. However, this also didn't help... Has anybody an idea what the problem might be and how I can get stable results for the variable importance measure?