Quarterly sales for a department store over a six-year period are given in the file P12_52.xlsx. a.
Question:
Quarterly sales for a department store over a six-year period are given in the file P12_52.xlsx.
a. Use multiple regression to develop an equation that can be used to predict future quarterly sales. (Hint: Use dummy variables for the quarters and a time variable for the quarter number, 1 to 24.)
Let X represent the quarter number (1-24).
Let X1 represent a dummy for first quarters.
Let X2 represent a dummy for second quarters.
Let X3 represent a dummy for third quarters.
If required, round your answers to one decimal place. For subtractive or negative numbers use a minus sign even if there is a + sign before the blank. (Example: -300)
Ŷ =______ + _______ X +_______ X1 +_______ X2 +________ X3
b. Letting Yt be the sales during quarter t, discuss how to estimate the following equation for this series.
Yt= abt1b2x1b3x2b4x3
Here X is a quarter, X1 is a dummy for first quarters, X2 is a dummy for second quarters, and X3 is a dummy for third quarters.
c. Based on your answer in part b develop a model that can be used to predict the logarithm of future quarterly sales.
Here X is a quarter, X1 is a dummy for first quarters, X2 is a dummy for second quarters, and X3 is a dummy for third quarters.
If required, round your answers to three decimal places. For subtractive or negative numbers use a minus sign even if there is a + sign before the blank. (Example: -300)
LogŶ = ______ +______ X +________ X1 +________ X2 +________ X3
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Elementary Statistics Picturing the World
ISBN: 978-0321911216
6th edition
Authors: Ron Larson, Betsy Farber