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Related Experiment Video

Updated: Jun 24, 2026

Observation and Quantification of Mating Behavior in the Pinewood Nematode, Bursaphelenchus xylophilus

Observation and Quantification of Mating Behavior in the Pinewood Nematode, Bursaphelenchus xylophilus

Published on: December 25, 2016

Analysis of first coitus.

Hein Stigum¹, Sven-Ove Samuelsen, Bente Traeen

¹Division of Epidemiology, Norwegian Institute of Public Health, Nydalen, 0404 Oslo, Norway. hein.stigum@fhi.no

Archives of Sexual Behavior

|March 31, 2009

Summary

Researchers analyzed age of coital debut in Norway, finding an additive parametric survival model better fits the data than the Cox model. This model revealed significant shifts in debut age across birth cohorts, with women reporting debut earlier in younger cohorts.

Area of Science:

Sociology
Demography
Public Health

Background:

Analysis of age of coital debut is crucial for understanding sexual behavior patterns.
Age of coital debut data presents analytical challenges due to whole-year reporting and missing values.

Purpose of the Study:

To identify a regression model that effectively analyzes age of coital debut data.
To find a model that provides simple and interpretable results for sexual behavior analysis.

Main Methods:

Utilized four cross-sectional surveys (1987-2002) of 18,000 Norwegian adults.
Compared Cox proportional hazards model with a linear parametric survival model.
Employed an additive parametric survival model, deemed superior for the dataset.

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Main Results:

The additive parametric survival model demonstrated a better fit and interpretability compared to the Cox model.
A significant decrease in age of coital debut was observed in cohorts born 1927-1984 (1 year for men, 2.3 years for women).
Gender differences in age of debut varied by cohort, with women debuting later in older cohorts and earlier in younger ones.

Conclusions:

Parametric survival models offer more interpretable results and better fit for age of coital debut data than the Cox model.
The study highlights substantial generational shifts in the age of sexual debut within the Norwegian population.
Findings underscore the importance of appropriate statistical methods for analyzing complex demographic and behavioral data.