Over the course of individual lifetimes, luck usually explains a large fraction of the between-
individual variation in lifespan or lifetime reproductive output (LRO) within a population, while
 variation in individual traits or “quality” explains much less. To understand how, where in the life cycle, and through which demographic processes luck trumps trait variation, we show how to partition by age the contributions of luck and trait variation to LRO variance, and how
to quantify three distinct components of luck. We apply these tools to several empirical case
studies.

We find that luck swamps effects of trait variation at all ages, primarily due to randomness
in individual state dynamics (“state trajectory luck”). Luck early in life is most important. Very
 early state trajectory luck generally determines whether or not an individual ever breeds, likely by ensuring that they are not dead or doomed quickly. Less early luck drives variation in success
among those breeding at least once. Consequently, the importance of luck often has a sharp
 peak early in life, or two peaks. We suggest that ages/stages where the importance luck peaks 
are potential targets for interventions to benefit a population of concern, different from those
 identified by eigenvalue elasticity analysis.

R code

The code should be self-contained.