Relation of observed cases to expected cases (numerator)

calculation of the expected cases with indirect age standardization

observed cases are based on 374 eligible cases identified for the case-control study (primary first NMSC) from a total of 541 cases (including secondary cancer cases)

Reference populations to calculate the numerator (expected cases):

(1) NMSC incidence of the district of Prievida, based on 374 eligible cases

(2) NMSC incidence of Slovakia
this number includes secondary NMSC, therefore SIR underestimates the ‚true‘ ratio of observed to expected cases

Breslow NE, Day NE, eds.