SquirrelMapper examines whether there is a difference in frequency of the black and gray types in different categories, such as different kinds of environments (urban versus rural, north versus south, etc.). To do this, we link every observation you report to a vast, global GIS database on land cover. Through this project we seek to get people of all ages outside looking at squirrels and thinking about the fascinating process of evolution that is unfolding around us every day.
A simple statistical test - the chi-square test - is used to determine if the observed pattern is substantially different from an expected pattern. "Substantially different" means that the chance of observed and expected being the same is very low, that is, a less than 1 in 20 chance or p < 0.05. Any test returning a result like this is considered "significant", that is, unlikely to have occurred by chance.