I am pretty slow when it comes to selecting statistical analysis. I am starting to analyze data for my thesis which come from an old experiment. The experiment was designed with 4 light intensity treatments (categorical) established in 5 replications or sites. Each treatment involved 15 seedlings. The other explanatory variables measured at the end of the experiment include slope, aspect and soil moisture. I hope to know the variation in plant height growth and percentage survival within sites and treatments and variations between sites and treatments. I tried modeling height using multiple regression, but I don't know if there would be more meaningful or appropriate analysis for my data.