A research study was conducted to examine the clinical efficacy of a new drug used to improve memory. Students were randomly assigned to one of four groups: a placebo group, a group that received a low dose of the drug, and a group that received a moderate dose of the drug, and a group that did not receive any dose. Students were administered their respective doses and had to study for a Spanish vocabulary test. The group who did not receive any drug, was just told to study for the test. None of the 43 students spoke Spanish. Below is an ANOVA table used to analyse the results from the test: Source SS df MS F Between XX XX XX XX Within XX 2 XX Total What is the missing value for the degrees of freedom for the "within" row (marked by a (?)