This made me wonder, is there really a significant "home bias" effect for counting shots. Who could have thought such a simple task would be subject to such variations?
So let's start with the last 4 years of shot data. The graph below shows a "Matrix Plot" of the ratio of Shots@home / Shots@road (only first 3 periods). All four seasons have some sort of positive correlation (I didn't check significance though for each). The reader should notice quite quickly that most of the values are greater than 1. Or that shots @ home is generally greater than shots on the road. This should not be a huge surprise - home teams also get more goals.
bigger copy with the names of teams
Ratio in 2008 = 0.42 + 0.61 x Ratio Average (2005,2006,2007) [p-value=0.001]
Ratio in 2008 = 1.07 + 0.61 x (Ratio Average - 1.07)
I've also included a data summary for all the ratio observations (4 seasons x 30 teams = 120 observations) to give the reader an idea of how the data is distributed.
There is obviously something going on here (sorry I'm trying to keep this short). It's worth noting that Colorado elevation provides them with a natural home advantage. However, even when you remove C0lorado from the data you get similar results.