Your logic has some flaws. Allow me to elucidate: The probability of you randomly selecting a sample of people who happen to have a high rate of cancer is very

Your logic has some flaws. Allow me to elucidate: The probability of you randomly selecting a sample of people who happen to have a high rate of cancer is very low. The probability of you EVENTUALLY selecting a sample of people who have a high rate of cancer after selecting many samples is actually very high. The probability of you eventually selecting a sample of people who happen to have a high rate of cancer AND happen to live in the same town AND happen to have cancers that are classified as rare is very very low. There is no doubt this is an anomaly by every logical measure and not a statistical quirk. This is an example of where your gut notion of a cancer cluster actually trumps the statistical logic. While logic is always correct and the logic you were using was technically wrong, this is a good example of how your intuitive gut feeling of what a cluster is, trumps your logical mind. Don't ignore your gut feelings, don't ignore your intuitions. The logical part of the human mind is just as flawed as your intuitions and it can build an incorrect scaffold of compositions that support an incorrect conclusion. When your logic collides with your intuitions, do not automatically assume that logic trumps all. Evaluate both.