A study tested whether cholesterol was reduced after using a certain brand of margarine as part of a low fat, low cholesterol diet.The subjects consumed on average 2.31g of the active ingredient, stanol easter, a day.This data set contains information on 18 people using margarine to reduce cholesterol over three time points.The data includes the ID of the person, before values, after 4 week values, after 8 week values and the Margine A or B. Each are columns in the data set. What ANOVA should I use for this data set and why? single factor, two factor with replication?

Thank you!