1. Monthly shoe sales (millions of dollars) were collected between January 2002 and December 2005 ("Shoe sales data.xlsx")
   1. Using the appropriate plots, how would you characterize the data? Explain
   2. Build a regression model to forecast sales
   3. Deseasonalize sales and build a regression model to forecast sales
   4. What is the seasonal index of the month of August? Interpret its meaning
   5. Using R², MAPE and RMSE, compare the fit of the models in part (b) and (c)

Date	Shoe_sales
Jan-02	1204
Feb-02	1286
Mar-02	1567
Apr-02	1625
May-02	1576
Jun-02	1490
Jul-02	1468
Aug-02	1872
Sep-02	1498
Oct-02	1475
Nov-02	1497
Dec-02	2038
Jan-03	1179
Feb-03	1237
Mar-03	1524
Apr-03	1607
May-03	1638
Jun-03	1556
Jul-03	1536
Aug-03	1970
Sep-03	1559
Oct-03	1501
Nov-03	1582
Dec-03	2154
Jan-04	1211
Feb-04	1310
Mar-04	1679
Apr-04	1655
May-04	1688
Jun-04	1587
Jul-04	1634
Aug-04	2042
Sep-04	1614
Oct-04	1594
Nov-04	1676
Dec-04	2219
Jan-05	1231
Feb-05	1240
Mar-05	1707
Apr-05	1758
May-05	1784
Jun-05	1700
Jul-05	1658
Aug-05	2085
Sep-05	1652
Oct-05	1596
Nov-05	1735
Dec-05	2231