I ran randomForest in R package using 7 predictors variables (x1 to x7). I repeated the test with 4 dependent variables (y1 to y4). The importance numbers (IncNodePurity) are plotted in following graph:
Does this mean that the predictors explain maximum variance of y4 than others? How do I know whether predictors are statistically significant or not? What additional test can I run to determine this? Thanks for your help.