For Exercises 13.38 and 13.39, see page 690.
13.40 MLB batting average.
Consider data on the annual average batting average of all Major League Baseball (MLB) teams of a given year. The data series begins with 1960 and ends with 2013.24
mlb
13.41 Amazon sales.
In Example 13.25, the one-step ahead forecast was calculated. Using the model of Example 13.25, determine the two-step ahead forecast in original dollar units.
13.41
Predlog(y60)=1.67+0.0131(60)− 0.6996(0)− 0.55212(0)− 0.4277(0)+ 0.8045(9.95556)= 10.46528. Undoing the transformation yields e10.46528=35076.27. PredSales=35076.27(1.0008)=$35,104.33.
13.42 MLB batting average.
Continue the analysis of MLB batting averages from Exercise 13.40.
mlb
13.43 OPEC basket prices.
In 2005, OPEC introduced a basket price which is the average price of seven blends from different OPEC countries. OPEC uses the basket price to monitor world oil market conditions. Consider data on the daily basket price from the beginning of January 2012 to the middle of August 2014.25
opec
13.43
(a) There is no consistent trend or seasonal pattern, but there are short runs where the value rises and falls. (b) The ACF shows the first differences of the price series are not random. (c) The first differences in a random walk are random; because the first differences for price are not random, it is unlikely the price series behaves like a random walk.
13.44 OPEC basket prices.
Continue the previous exercise.
opec
13.45 Warehouse club and superstore sales.
Consider the warehouse club and superstore sales series discussed in Examples 13.15 and 13.16 (pages 671–674).
club
13.45
(a) Sales is linearly related to lag12sales. (b) r=0.97021. (c) P-value<0.0001. There is a significant linear relationship between this month’s sales and sales 12 months ago.