Examine the effect of point-orbit ages on hazard profiles

Determine how the entry- and exit-age distribution of point orbits affects the estimated hazard profile in event-history analyses of early-life child mortality.

Background

Point orbits represent children observed at only one age and therefore contribute to state-space occupancy without providing transition information. They are excluded from transition-based Orbit Theory analysis but still contribute to the denominator of the event-history hazard estimates.

The paper identifies an unresolved issue concerning whether the ages at which these single-observation trajectories enter and leave observation influence the estimated hazard profile, particularly because point orbits may be non-randomly distributed across ages and covariate configurations.

References

Finally, point orbits - children observed only once across the five-year window - contribute to state-space occupancy but carry no transition information; their entry and exit age distribution may affect the hazard profile in ways not yet formally examined.

— State-space representation of early-life child mortality dynamics: linking event history analysis and orbit-based models  (2610.07877 - Lefotlha et al., 6 Oct 2026) in Conclusion, future-work paragraph