Exercise 1: (Calculations must be done by a calculator, except possibly question c) In the United States, repeated tests to the doctoral admission exam (Graduate Record Examination or GRE)

Make it possible to improve the scores obtained, even without any study does not intervene. 8 subjects passed the oral part of the GRE for 3 weeks.

The results are grouped in the following table:

Subject	Week 1	Week 2	Week 3
1	550	570	580
2	440	440	470
3	610	630	610
4	650	670	670
5	400	460	450
6	700	680	710
7	490	510	510
8	580	550	590

a) Give a statistical model applicable to this data.

b)Perform the analysis of this experience plan and give your conclusion.

c) By calculating the covariance matrix of these data. Are the Conditions of application of the method are met. Explain your Answer.

d) Redo the previous exercise with the R software.

Note: Reference: Analysis of experience plans MAT3378