It's good to see you again In this chpater, I tried to make a variable Firtst, load a dataset(whatever you use) check my dataset.. 2590 objects, and 378 variables in data now, make a variable by 'apply' function how to use it? apply(dataset[,column number:column number],1,mean) dataset : set your data [,column number:column number] : becareful 'comma' place and select column number for variable ..