Every couple of years in February I get around to writing about Super Bowl squares. It’s been a few years, so I decided to update the post. So here is the updated 2 dimensional histogram of how often certain numbers occur in Super Bowl squares.  Nothing new here.  You want to get some combination of 7-0 or 0-7 followed by 7-7, 7-4, and 4-7.  3-0, 4-0, and 0-0 are also good.  Try not to get 2-2. (Though it does happen).

Next, rather than looking at 7-0 and 0-7 as different, I let those count as the same outcome giving the following 2 dimensional histogram.  Basically the same amount of information — You want 7-0 and you don’t want 2-2.

Next, what I was wondering about was how this changed over time.  Here is a plot of each end digit for all games played by season.  The most notable part of this graph is that 0 dropped very rapidly from 1920-1960 stemming from far fewer games ending with one team getting shut out.  You can also see some other smaller trends over this time period such as 1, 7, 4, and 8 increasing with 6 and 3 decreasing.  But this plot is kind of a mess and there are way too many lines on it.  Let’s use facet_wrap().

Ahh!  Much easier to trends in numbers over time.  Let’s go through these number by number.  0 dropped rapidly from 1920 – 1960 then increased slightly until about 1980 when it began another small decline.  1 increased quickly and has basically been flat since the 1970s.  2 has been flat forever.  3 has a small decline through 1940, but has been slowly increasing ever since.  4 looks like it peaked in 1950 and has been slowly dropping since then.  5 is basically 2 — flat.  6 follows roughly the same pattern as 3 — a small decrease until 1950 and then slowly increasing.  7 peaked in 1940 and has been slowly decreasing since then.  8 peaked in 1950 came back down and has been flat since 1970.  Finally, 9 has been basically flat.

Lastly, another way to look at this is with a heat map over time.  The plot below shows the relative frequency of last digits over time with dark red indicating large numbers and dark blue indicating low numbers.

All the code for generating these plots can be found here.

Cheers.