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I was reading this paper related to Bayesian spatial scan statistics where I came across the Kulldorff's scan statistics.

I have attached the screenshot of the paper. My objective is to find a location of potential disease outbreak.

enter image description here

I have a little doubt with the formula given in the paper. In the paper it is mentioned that the Fscore of any location is

enter image description here

My question is when they calculate the F score.

The number of sick people in current location(Cin) = 5 The baseline population is around(Bin) 50 The number of sick people outside current location(Cout) = 2245 The number of sick people outside current location(Bout) = 62475

Call = 5+2245 = 2250 Ball = 50+62475 = 62525

Now if I calculate the Fscore it comes out to be Nan. Is it the correct formula? Any insights

In the next link I found something like this

enter image description here

Now even though I use this formula, the value is NaN. It is because like in the case of denominator the prob < 1 and I am raising it to a high power, so it comes out to be zero. So my question is, is it the problem with my data itself? If I plug it into the formula it will definitely come out to be like that.

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