TABLE 5.

Calculated O/E Ratio for the Hypothetical Hospital Data Given in Table 4

Total no. of newborns in all 50 cells of the hypothetical hospital column in Table 4 (as posited):3526
Expected events as computed*:  167.8Expected risk:  167.8/3526 = 4.8%
Observed events as posited:  300.0Observed risk:  300/3526 = 8.5%
O/E:  300/167.8O/E ratio:  1.8
  • Expected events are calculated by applying the following formula to the 50 cells of the hypothetical hospital data in Table 4.

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    where Pi is the predicted probability in cell i, i = 1, 2, 3, . . . 50, and fi is the corresponding frequencies in the hypothetical hospital.