Statistics: Hypothesis Testing – #57


Question: Consider the quarterly sales given in the table below.

Quarterly Sales
Year Net Sales (millions)
1996 $4,053
1996 5,075
1996 5,159
1996 6,050
1997 4,213
1997 5,086
1997 5,362
1997 6,256
1998 4,353
1998 5,258
1998 5,544
1998 7,193
1999 5,114
1999 4,982
1999 4,591
1999 5,680
2000 4,191
2000 4,928
2000 4,909
2000 6,410

a. Draw a time series plot for this data set and describe any trend and seasonal behavior that you see.

b. Plot the moving average values on the same graph as the original data. (4 quarters)

c. Find the seasonal index for each quarter. Which is generally the best quarter for sales?

d. Plot the seasonally adjusted series with the original data.

e. Find the regression equation to predict the long-term trend in seasonally adjusted sales for each time period. Does the trend equation show a significant trend over time.

only-members
 

log in

reset password

Back to
log in