You also have to consider that the Hays, KS hospital, being a much smaller hospital, has a much smaller number of cases. The confidence interval around that is

You also have to consider that the Hays, KS hospital, being a much smaller hospital, has a much smaller number of cases. The confidence interval around that is definitely larger as a result. Not sure how much larger, but likely enough to make the difference statistically insignificant (town pop is 21k, heart surgery # is likely very low). Put another way, a single death out of a small population of patients will have a larger impact on the statistics.