Graphing Predicted Velocity, or xMPH

Today I reached the section of Analyzing Baseball Data with R, in which traditional graphing was covered. The section taught bar graphs, line graphs, scatter plots, boxplots, stripcharts and the like. It ended in several activities, such as this comparison of the cumulative sum of home runs of four pretty decent hitters:

what am i doing

Not sure if that’s how the legend is supposed to appear.

Having learned (?) this, I decided to prepare several graphs of the data I analyzed from Driveline. There’s nothing new here, just a representation of my research.

boxplot for each athlete

I started off with a boxplot. This shows the velo range for each athlete, 1 through 5. As you can see, athlete 3 was expected to have thrown the hardest, projected between 79 and 84.

The second graph I created was made with plotrix and plotCI(). I plotted the upper and lower fits as error bars as well as the predicted fit (xMPH). Each athlete got 20 throws, so each denomination of 20 is a new athlete as shown by their grouping on the graph. Athlete #2 had a good deal of variation in his throws relative to others.

This is just a basic plot showing the xMPH by throw. As we can see, there are small spikes here and there but all in all, there’s nothing to suggest any fatigue after the 20 pitches.


Originally published at danolytics.wordpress.com on August 16, 2016.

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