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

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

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.

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

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.