Pearson's chi squared test.
|:: (Vector v (Int, Double), Vector v Double)|
Number of additional degrees of freedom. One degree of freedom is due to the fact that the are N observation in total and accounted for automatically.
|-> v (Int, Double)|
Observation and expectation.
Generic form of Pearson chi squared tests for binned data. Data sample is supplied in form of tuples (observed quantity, expected number of events). Both must be positive.