Nonpaternity and Half-Siblingships as Objective Measures of Extramarital Sex: Mathematical Modeling and Simulations

Table 1

Key model assumptions in terms of parameter values.

Description	Symbol	Value	Reference
Marriage rate		0.12 per year	Estimated from Kenya’s 2008-2009 DHS data [27]
Mean duration of martial partnership		20 years	Representative value informed by Kenya’s 2008-2009 DHS data [27]
Mean duration of nonmarital (casual) sexual partnership		6 months	Representative value
Gestation period			[28]
Mean		267 days
Standard deviation		10 days
Number of premarital sex partnerships among unmarried women over the last year			Estimated from Kenya’s 2008-2009 DHS data [27]. Range is estimated based on DHS data for 20 Sub-Saharan African countries [8]
Mean		0.32 and a range of 0.0–1.0
Variance		0.0087 and a range of 0.0–2.0
Number of extramarital sex partnerships among married women over the last year			Estimated from Kenya’s 2008-2009 DHS data [27]. Range is estimated based on DHS data for 20 Sub-Saharan African countries [8]
Mean		0.0088 and a range of 0.0–0.5
Variance		0.0 with a range of 0.0–1.0
Fraction of coital acts that are with the spouse as opposed to an extramarital partner		0.7 and a range of 0.1–0.9	Representative but variable by objective of each specific analysis
Partnership-specific condom use coverage			Estimated from Kenya’s 2008-2009 DHS data [27]
Unmarried women		0.23
Marital sex among married women		0.019
Extramarital sex among married women		0.074
Efficacy of condoms in preventing conception	Eff	0.90	[29]

DHS: Demographic and Health Survey.