Question

Time-Series Graphs. In Exercises 9 and 10, construct the time-series graph.

Home Runs Listed below are the numbers of home runs in Major League Baseball for each year beginning with 1990 (listed in order by row). Is there a trend?

3317 3383 3038 4030 3306 4081 4962 4640 5064 5528 5693 5458 5059 5207 5451 5017 5386 4957 4878 5042 4613 4552 4934 4661

Short answer

The following time-series graph is constructed for the number of home runs in Major League Baseball for the years 1990 to 2013.

It can be observed that there is an upward trend initially from the year 1990 till 2001.

After 2012, there is no major trend in the number of home runs as the values have increased and decreased abruptly.

Step-by-step solution

Given information

The data provided concerns the number of home runs in the Major Baseball League starting from the year 1990.

3317 3383 3038 4030 3306 4081 4962 4640 5064 5528 5693 5458 5059 5207 5451 5017 5386 4957 4878 5042 4613 4552 4934 4661

Describe time-series plot

A graphical representation of a time-based set of observations is known as a time series plot.

Time duration can be scaled on years or months, marked on the horizontal axis. The observations are plotted as observations on the graph, and then all of them are connected to form a trend line.

Sketch the time series plot

The following table shows the number of home runs for the years 1990 to 2013.

Number of Home Runs	3317	3383	3038	4030	3306	4081
Year	1990	1991	1992	1993	1994	1995
Number of Home Runs	4962	4640	5064	5528	5693	5458
Year	1996	1997	1998	1999	2000	2001
Number of Home Runs	5059	5207	5451	5017	5386	4957
Year	2002	2003	2004	2005	2006	2007
Number of Home Runs	4878	5042	4613	4552	4934	4661
Year	2008	2009	2010	2011	2012	2013

The steps to sketch the time-series plot are as follows:

• Plot the values on the vertical axis starting from 2500 until 6000, with a gap of 500 units.
• Plot the values on the horizontal axis starting from 1990 until 2012, with a gap of two years.
• Mark the points on the graphs corresponding to the given year.
• Join the points with a line.
• Label the horizontal axis as “Year” and the vertical axis as “Number of Home Runs.”
  
  

The following time-series graph is constructed:

Describe the trend from the plot

The trend is observed as an approximate change in the observations.

By observing the plot, it can be seen that the number of home runs first increases until the year 2001 and then becomes more or less constant.