If you're using a while loop in R to iterate over a vector, you must manually increment the index variable with each loop. The increment operation in R is written as ______.

If you're using a while loop in R to iterate over a vector, you must manually increment the index variable with each loop. In R, the increment operation is written as 'index = index + 1'. This statement updates the value of the index variable by adding 1 to it. By incrementing the index within the loop, you can iterate through the elements of a vector.