A cognitive psychologist wants to investigate whether memory for a shopping list is affected by the strategy used to study the list. She selects 20 random students and assigns each of them randomly to one of four different groups. Each group is given a different strategy by which to study the list. After the students study the list, they try to recall as many items as they can. The number of items remembered from the list for each students is given below.
Is there sufficient evidence to conclude that different strategies lead to different memory performance? Use significance level 0.05