First let me preface with I tried to search for this solution first but I don't really know how to word it and could not find any results so excuse me if this is a duplicate. I would like to know how to prove or test to show if this problem is statistically significant or not.
I am using Arc 10.3.1 and have a feature class of incidents and a feature class of roads. I queried out the major roads and buffered them to find out how many incidents fall within that road buffer.
I have approximately 6000 miles of roads. Of that 6000 miles, 900 miles are a major road. I also have 2010 incidents. Of those incidents 725 occurred on a major road. (ie 15% of the roads account for 35% of the problems) I would like to know of tutorial or guide that would show me how to prove or not prove if the incidents on a major road are significant or not.
Answer
Finding the "right" test is often a difficult task. I'm reading through the problem you are formulating and I'm thinking to start out we don't actually need to look at this problem spatially, at all. I'm suggesting a Chi-Squared test to compare the counts of incidents between the major and non-major roads for significant difference to start. From there maybe find a test that can compare crash rates.
I'm a fan of looking over the dataset and finding the simplest possible test and applying that one first. Hopefully, the simplest test will give you a hint towards choosing a more complex test, or an indicator that explicitly considers space in its formulation. Satisfying or adjusting for stationarity assumptions for most spatial stats is hard enough as it is. Further, only a few people I know of really really really have dealt with questions of spatial stats constrained to network space.
It's such a huge subject. I fear it even though I love GIS.
Best Luck here.
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