Question

Time Series Analysis 3. Wonder-Z electronics Store is considering the sales pattern of the gaming consoles they self-manufacture. They provide you with the following data from the past five years, by seasons:

Year	1	2	3	4	5
Quarter	1     2    3     4	1      2     3     4	1      2     3      4	1      2       3      4	1       2      3     4
Sales (1000's)	85 79 120 130	115 95 135 145	122 110 155 158	130 122 162 170	125 105 165 180

a. Construct a time series plot and identify the pattern exists in the data?

b. Use time series linear regression analysis using dummies for Q1, Q2, and Q3 and include time period “t” to find the parameters for the line that minimizes MSE for this data.

c. What is the forecast for the second quarter sales in the 6th year?

Answer 1

data

a)

b)

Using Excel

data -> data analysis -> regression

y^ = 125.4 +2.6 t -33.4 Q1 - 49.2 Q2 -6.6 Q3

c)

for 2nd quarted 6th year

t = 22, Q1 = 0,Q2 = 1, Q3 = 0

y^ = 125.4 +2.6 *22 -33.4*0 - 49.2 *1 -6.6*0

= 133.4

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