Life tables arrange observations from a cohort to show survival and mortality across successive points in the life course. They can summarize how many individuals remain under observation, how survival changes over time, and when deaths occur. This structure allows researchers to compare longevity patterns among populations, environments, biological conditions, or experimental groups.
A survival curve shows how the proportion of a cohort surviving changes over time, whereas a hazard rate describes how mortality risk changes during the life course. Considering both views helps distinguish overall longevity from periods when risk rises, falls, or differs between groups. Together, they provide complementary evidence about aging and mortality patterns.
Censored observations represent individuals whose complete life span is not available within the study period or observation record. Accounting for them prevents the analysis from treating incomplete follow-up as if it were a known death time. This produces more appropriate survival and hazard estimates when comparing cohorts observed over time.
Changes in mortality risk can be examined in relation to age, reproductive strategies, disease effects, environmental pressures, and other biological conditions represented in the study design. Comparing survival patterns across these factors may show whether mortality differs between species or experimental groups and identify conditions associated with longer or shorter life spans.
Researchers first define the cohort and follow individuals over time, recording survival status and relevant biological or environmental conditions. They then organize the observations with life tables, display survival with curves, and examine changing mortality using hazard rates. Censored observations must be retained appropriately so incomplete follow-up does not distort comparisons.
Biologists use this approach to compare aging patterns, reproductive strategies, disease effects, and environmental pressures across species or experimental groups. The resulting survival and mortality measures can identify factors associated with longevity and mortality. They also support evolutionary and ecological research, as well as investigations of aging and health.