Casual Contraception in Casual Sex
Supplement F: Intermediate Models

Supplemental Table F1. Intermediate Models
Models Estimating the Odds of Coitus Models Estimating the Odds of Condom Use
Eq. 2 Eq. 2, Grade Dichotomy Eq. 3, Grade × SES Eq. 3, Grade × School Gender Composition Eq. 3, Years234 × SES Eq. 3 Eq. 2 Eq. 2, Grade Dichotomy Eq. 3, Grade × SES Eq. 3, Grade × School Gender Composition Eq. 3, Years234 × SES Eq. 3
WomenMenEitherWomenMenEitherWomenMenEitherWomenMenEitherWomenMenEitherWomenMenEitherWomenMenEitherWomenMenEitherWomenMenEitherWomenMenEitherWomenMenEitherWomenMenEither
Year of College
Freshman Year
Sophomore Year1.29***1.53***1.35***1.56**1.46^1.51***1.061.62***1.27**0.68**0.62*0.67***0.47**0.28**0.40***0.55***0.66^0.62***
Junior Year1.79***1.53***1.68***1.65***0.961.37*1.25*1.41*1.32**0.72**0.63*0.69***0.680.38*0.56*0.66*0.730.69*
Senior Year2.09***2.27***2.10***2.12***1.76*1.94***1.52***2.43***1.81***0.63***0.62*0.62***0.51**0.38*0.46***0.69*0.57*0.67**
During/After Freshman Year
First Year of College
Years 2/3/4 of College1.55***1.71***1.65***1.63***1.36^1.56***1.31*1.371.37**0.68***0.62**0.66***0.54**0.34**0.46***0.51**0.36*0.46***
Mother's Educational Attainment
Mother Received a High School Education or Less
Mother Received Some College Education0.85*0.870.87*0.85*0.860.87*0.830.72^0.80^0.85*0.870.87*0.830.72^0.81^0.830.720.80^0.920.900.920.920.900.920.900.47^0.750.910.890.920.900.47^0.740.900.46^0.74
Mother Received a Bachelor's Degree0.80**0.940.85**0.80**0.930.85**0.890.770.850.80**0.940.85**0.900.770.860.880.770.850.861.030.920.861.030.920.730.730.72^0.851.020.920.730.730.72^0.730.740.72^
Mother Received a Graduate Degree0.84*0.73*0.82**0.84*0.73*0.81**0.830.58*0.75*0.84*0.73*0.82**0.830.58**0.76*0.820.58**0.76*0.890.800.880.890.800.880.55*0.35*0.48***0.900.790.880.55*0.35*0.48***0.55*0.35*0.48***
Year of College × Mother's Educational Attainment
Sophomore × Some College0.941.130.991.382.85^1.76^
Junior × Some College1.171.94*1.36^0.902.331.20
Senior × Some College1.021.101.040.891.761.06
Sophomore × Bachelor's Degree0.67*1.020.791.501.981.71^
Junior × Bachelor's Degree1.021.84*1.251.021.201.11
Senior × Bachelor's Degree0.911.361.051.211.441.33
Sophomore × Graduate Degree0.801.060.882.09*3.71*2.57**
Junior × Graduate Degree1.251.601.311.362.611.65
Senior × Graduate Degree1.081.71^1.272.31*2.442.42**
Grade × Mother's Educational Attainment
Years 2/3/4 × Some College1.031.321.101.031.311.101.042.35^1.331.022.35^1.32
Years 2/3/4 × Bachelor's Degree0.841.310.970.831.310.981.241.551.381.221.511.37
Years 2/3/4 × Graduate Degree1.021.401.121.001.401.121.90*2.94*2.21**1.92*2.94*2.22**
School Gender Composition
≤ 53% Female
≥ 53% Female0.921.060.84*1.141.060.82*1.051.171.081.051.211.08
≥ 53% Female × Years 2/3/41.50***0.971.31**1.130.861.00
≥ 53% Female × Sophomore1.39*0.871.151.480.861.18
≥ 53% Female × Junior1.81***1.201.60***1.150.730.98
≥ 53% Female × Senior1.71***0.851.35*0.831.170.87
Observations714431311027571443131102757144313110275714431311027571443131102757144313110275258212523834258212523834258212523834258212523834258212523834258212523834
Supplemental Table F2. Intermediate Models, With School-Fixed-Effects (Instead of Random Effects)
Models Estimating the Odds of Coitus Models Estimating the Odds of Condom Use
Eq. 2, Grade Dichotomy Eq. 3, Grade × SES Eq. 3, Grade × School Gender Composition Eq. 2, Grade Dichotomy Eq. 3, Grade × SES Eq. 3, Grade × School Gender Composition
WomenMenWomenMenWomenMenWomenMenWomenMenWomenMen
Year of College
Freshman Year
Sophomore Year1.51**1.48^1.111.63***0.47**0.31**0.55***0.65^
Junior Year1.57**0.971.31*1.39*0.690.41^0.66*0.73
Senior Year2.04***1.76*1.61***2.44***0.53*0.41^0.72^0.56*
During/After Freshman Year
First Year of College
Years 2/3/4 of College1.59***1.71***0.69***0.60**
Mother's Educational Attainment
Mother Received a High School Education or Less
Mother Received Some College Education0.86*0.880.840.730.85*0.890.920.870.850.520.920.86
Mother Received a Bachelor's Degree0.81**0.950.910.790.81**0.960.841.020.710.800.841.02
Mother Received a Graduate Degree0.86^0.76*0.850.60*0.87^0.76*0.850.750.54*0.35*0.850.74
Year of College × Mother's Educational Attainment
Sophomore × Some College0.941.111.472.34
Junior × Some College1.171.91*0.941.94
Senior × Some College1.001.100.971.50
Sophomore × Bachelor's Degree0.68*1.011.551.83
Junior × Bachelor's Degree1.031.82*1.021.05
Senior × Bachelor's Degree0.901.361.201.22
Sophomore × Graduate Degree0.821.062.11*3.30*
Junior × Graduate Degree1.271.591.302.46
Senior × Graduate Degree1.101.73^2.22*2.15
≥ 53% Female * 1.28^0.871.60^0.84
≥ 53% Female * 1.66***1.221.230.67
≥ 53% Female * 1.53**0.850.871.10
Observations714431317144313171443131258212512582125125821251
Supplemental Table F3. Intermediate Models
Models Estimating the Odds of Coitus Models Estimating the Odds of Condom Use
Eq. 2 Eq. 2, Grade Dichotomy Eq. 3, Grade × SES Eq. 3, Grade × School Gender Composition Eq. 3, Years234 × SES Eq. 3 Eq. 2 Eq. 2, Grade Dichotomy Eq. 3, Grade × SES Eq. 3, Grade × School Gender Composition Eq. 3, Years234 × SES Eq. 3
WomenMenEitherWomenMenEitherWomenMenEitherWomenMenEitherWomenMenEitherWomenMenEitherWomenMenEitherWomenMenEitherWomenMenEitherWomenMenEitherWomenMenEitherWomenMenEither
Year of College
Freshman Year
Sophomore Year1.121.59***1.31***1.63*1.191.44*1.101.65**1.26*0.56***0.60*0.58***0.30**0.27*0.27***0.40***0.640.49***
Junior Year1.57***1.64***1.68***1.63*0.701.201.32*1.46*1.34**0.69*0.59^0.66**0.470.27^0.38*0.49**0.760.58**
Senior Year1.74***2.15***1.98***1.98**1.471.75**1.56**2.00***1.69***0.60**0.51*0.58***0.31**0.29^0.29***0.58*0.39**0.52***
During/After Freshman Year
First Year of College
Years 2/3/4 of College1.41***1.74***1.62***1.72***1.091.45**1.301.071.250.62***0.57*0.60***0.34**0.27*0.30***0.26**0.32^0.26***
Mother's Educational Attainment
Mother Received a High School Education or Less
Mother Received Some College Education0.910.960.930.910.960.930.980.660.860.890.950.920.980.670.860.980.670.860.800.770.800.800.770.800.580.29^0.45*0.790.750.790.580.29^0.46*0.580.29^0.45*
Mother Received a Bachelor's Degree0.870.970.910.860.970.911.010.700.870.870.970.911.010.700.870.990.710.880.63*0.830.71*0.63*0.830.71*0.38*0.710.42*0.61**0.810.70*0.37*0.710.42*0.37*0.780.42**
Mother Received a Graduate Degree0.870.860.880.880.850.900.950.51**0.76^0.890.850.890.940.51**0.76^0.930.51**0.77^0.62*0.650.66*0.62*0.650.66*0.29**0.22*0.27***0.62*0.610.66*0.29**0.22*0.27***0.29**0.22*0.27***
Year of College × Mother's Educational Attainment
Sophomore × Some College0.781.571.001.493.672.19^
Junior × Some College1.003.05**1.48^1.474.012.04
Senior × Some College0.961.171.021.412.741.75
Sophomore × Bachelor's Degree0.58*1.270.772.301.282.22^
Junior × Bachelor's Degree1.042.60*1.45^1.431.051.45
Senior × Bachelor's Degree0.991.491.162.051.221.98
Sophomore × Graduate Degree0.751.560.972.55^5.00^3.39**
Junior × Graduate Degree1.183.03**1.60^1.874.97^2.58^
Senior × Graduate Degree0.982.38*1.343.67*2.773.49**
Grade × Mother's Educational Attainment
Years 2/3/4 × Some College0.901.73^1.130.891.71^1.111.483.50^2.04^1.453.40^2.01^
Years 2/3/4 × Bachelor's Degree0.811.62^1.050.811.61^1.041.951.201.91^1.901.061.88^
Years 2/3/4 × Graduate Degree0.952.15*1.250.942.15*1.252.72*4.01^3.23**2.81*3.85^3.24**
School Gender Composition
≤ 53% Female
≥ 53% Female1.171.100.80^0.881.121.070.871.810.940.862.000.94
≥ 53% Female × Years 2/3/41.64***1.071.37**1.68^0.741.35
≥ 53% Female × Sophomore1.240.901.152.02*0.781.49
≥ 53% Female × Junior1.69**1.281.64**1.89^0.551.27
≥ 53% Female × Senior1.57*1.171.51**1.111.541.24
Observations429421076401429421076401429421076401429421076401429421076401429421076401137578421591375784215913757842159137578421591375784215913757842159
Supplemental Table F4. Intermediate Models
Models Estimating the Odds of Coitus Models Estimating the Odds of Condom Use
Eq. 2 Eq. 2, Grade Dichotomy Eq. 3, Grade × SES Eq. 3, Grade × School Gender Composition Eq. 3, Years234 × SES Eq. 3 Eq. 2 Eq. 2, Grade Dichotomy Eq. 3, Grade × SES Eq. 3, Grade × School Gender Composition Eq. 3, Years234 × SES Eq. 3
WomenMenEitherWomenMenEitherWomenMenEitherWomenMenEitherWomenMenEitherWomenMenEitherWomenMenEitherWomenMenEitherWomenMenEitherWomenMenEitherWomenMenEitherWomenMenEither
Year of College
Freshman Year
Sophomore Year1.31*1.241.31**1.46^1.781.58*1.141.211.210.860.680.840.54^0.27^0.49*0.800.670.84
Junior Year1.68***1.271.55***1.42^1.441.42^1.281.161.240.820.740.820.820.520.770.980.680.92
Senior Year2.00***2.31***2.00***1.96**2.19*2.00***1.67**2.66***1.86***0.73^0.910.77^0.730.590.710.970.920.97
During/After Freshman Year
First Year of College
Years 2/3/4 of College1.63***1.47**1.58***1.58**1.76^1.63**1.321.76^1.43*0.800.770.81^0.700.440.65^0.800.430.74
Mother's Educational Attainment
Mother Received a High School Education or Less
Mother Received Some College Education0.78*0.810.79*0.78*0.760.78**0.66^0.740.70^0.78*0.810.78*0.67^0.740.70^0.66^0.740.70^0.940.980.960.940.970.960.920.750.920.930.980.950.920.750.910.930.740.92
Mother Received a Bachelor's Degree0.74**0.950.80*0.73**0.920.79*0.781.060.850.74**0.960.80*0.781.070.860.781.070.860.981.021.030.971.021.030.980.510.890.981.021.040.980.510.890.960.510.88
Mother Received a Graduate Degree0.80^0.62*0.73**0.78^0.62*0.72**0.750.900.800.81^0.62*0.74**0.750.920.810.770.920.811.110.741.041.110.741.030.650.390.601.120.741.040.640.390.600.630.390.60
Year of College × Mother's Educational Attainment
Sophomore × Some College1.100.790.961.942.141.88
Junior × Some College1.481.231.390.871.350.93
Senior × Some College1.111.681.120.760.910.77
Sophomore × Bachelor's Degree0.790.610.751.354.05^1.74
Junior × Bachelor's Degree1.090.941.070.891.961.07
Senior × Bachelor's Degree0.881.100.890.851.881.01
Sophomore × Graduate Degree0.780.550.683.15*3.863.01*
Junior × Graduate Degree1.310.460.931.501.021.34
Senior × Graduate Degree1.270.721.041.942.622.14^
Grade × Mother's Educational Attainment
Years 2/3/4 × Some College1.231.041.141.231.041.141.041.401.081.041.421.08
Years 2/3/4 × Bachelor's Degree0.910.820.890.910.810.880.992.461.221.002.481.23
Years 2/3/4 × Graduate Degree1.050.570.861.040.570.852.06^2.342.07*2.09^2.332.09*
School Gender Composition
≤ 53% Female
≥ 53% Female1.011.010.891.000.970.861.400.871.221.410.861.24
≥ 53% Female × Years 2/3/41.39^1.011.290.741.080.76
≥ 53% Female × Sophomore1.281.071.191.071.080.98
≥ 53% Female × Junior1.56^1.201.51*0.701.210.78
≥ 53% Female × Senior1.350.691.150.580.950.61
Observations277896737452778967374527789673745277896737452778967374527789673745119944816471199448164711994481647119944816471199448164711994481647