1.   And, for investors, those chance occurrences become a form of entrapment.

2.   It can also be difficult to know if a cluster is anything more than a chance occurrence.

3.   Many will see a mystical connection between the events rather than view them as a weird but statistically plausible chance occurrence.

4.   That was not a chance occurrence.

5.   A chance occurrence, perhaps?

6.   State and federal health officials have investigated a variety of conceivable causes in recent months, including the possibility that the cluster is simply a chance occurrence.

7.   The researchers said the latter conditions could have been a chance occurrence but warrant further study.