Table 2.

Wald χ2 tests for estimable functions in the APC model*

Null hypothesisImplicationsDegrees of freedom
Net drift equals 0Fitted temporal trends are stable over time. Fitted longitudinal and cross-sectional age curves are proportional.Embedded Image
All age deviations equal 0Fitted longitudinal and cross-sectional age curves are log-linear.Embedded Image
All period deviations equal 0Fitted temporal trends and period rate ratios are log-linear.Embedded Image
All cohort deviations equal 0Cohort rate ratios are log-linear; all local drifts equal the net drift.Embedded Image
All period rate ratios equal 1Net drift is 0 and fitted temporal trends are constant; Cross-sectional age curve describes age incidence pattern in every period.Embedded Image
All cohort rate ratios equal 1Net drift is 0, and all local drifts are 0; Longitudinal age curve describes age incidence in every cohort.Embedded Image
All local drifts equal the net driftTemporal trends are the same in every age group.Embedded Image
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  • *For APC model defined over Embedded Image age groups, Embedded Image calendar periods, and Embedded Image birth cohorts.