Casual Contraception in Casual Sex
Trends by SES, Without Collapsing Grade into a Dichotomy

Supplemental Table D1. Selected Odds Ratios for Equation 3 Altered To Produce Estimates for Years 1, 2 and 3 separately, relative to Year 1, rather than contrasting Years 2, 3 and 4 together with Year 1
Models Estimating the Odds of Coitus Models Estimating the Odds of Condom Use
All Events Partner Attends Same College Partner Not From Respondent's College All Events Partner Attends Same College Partner Not From Respondent's College
WomenMenEitherWomenMenEitherWomenMenEitherWomenMenEitherWomenMenEitherWomenMenEither
Year of College
Freshman Year
Sophomore Year1.271.55^1.41**1.381.231.34^1.271.721.45^0.38***0.31**0.37***0.21***0.32^0.22***0.53^0.26^0.51*
Junior Year1.150.901.101.200.640.981.081.321.130.620.450.57*0.35*0.370.34*0.980.470.88
Senior Year1.56**1.87*1.69***1.49^1.401.48*1.65*2.54*1.85**0.55*0.37*0.49**0.28**0.27^0.26***0.950.610.89
Mother's Educational Attainment
Mother Received a High School Education or Less
Mother Received Some College Education0.820.72^0.81^0.980.66^0.860.66^0.750.70^0.900.46^0.740.580.30^0.45*0.930.750.92
Mother Received a Bachelor's Degree0.880.770.861.000.700.880.781.070.860.730.740.72^0.37*0.790.42**0.970.510.89
Mother Received a Graduate Degree0.840.58**0.76*0.940.51**0.77^0.770.910.810.55*0.35*0.48***0.29**0.22*0.27***0.640.390.60
Year of College × Mother's Educational Attainment
Sophomore × Some College0.971.141.010.801.591.011.100.790.961.362.88^1.73^1.573.572.22^1.812.191.81
Junior × Some College1.161.91*1.320.932.99**1.401.491.231.390.882.351.201.334.242.000.871.360.92
Senior × Some College1.011.111.030.931.140.981.101.651.130.881.701.071.402.371.720.760.900.76
Sophomore × Bachelor's Degree0.68*1.010.790.59*1.290.780.800.610.741.451.951.69^2.251.132.18^1.314.10^1.74
Junior × Bachelor's Degree1.021.82*1.221.002.55*1.411.070.941.071.011.171.111.330.951.440.911.951.07
Senior × Bachelor's Degree0.891.371.040.961.461.120.861.090.891.231.341.342.070.951.940.901.911.06
Sophomore × Graduate Degree0.801.070.880.751.590.970.760.550.672.16*3.72*2.61**2.82^4.79^3.54**3.16*3.893.03*
Junior × Graduate Degree1.241.571.301.132.96**1.55^1.320.460.951.382.631.651.815.01^2.56^1.510.991.35
Senior × Graduate Degree1.061.73^1.250.962.35*1.311.230.701.022.31*2.312.43**3.73*2.133.49**2.022.702.21^
School Gender Composition
≤ 53% Female
≥ 53% Female0.921.070.85*0.901.131.071.010.980.881.061.211.080.862.100.941.410.841.24
≥ 53% Female × Sophomore1.39*0.861.151.340.881.131.281.081.191.480.821.172.06*0.681.501.011.150.92
≥ 53% Female × Junior1.80***1.171.58***1.84**1.211.54**1.57^1.211.51*1.150.690.981.93^0.481.270.681.320.76
≥ 53% Female × Senior1.70***0.851.35*1.74**1.151.47*1.360.711.170.841.130.871.191.411.250.570.910.60^
Observations7144313110275429421076401277896737452582125238341375784215911994481647
Supplemental Table D2. Selected Odds Ratios for Equation 3 Reestimated Without Controls, And With Estimates for Years 1, 2 and 3 separately, relative to Year 1, rather than contrasting Years 2, 3 and 4 together with Year 1
Models Estimating the Odds of Coitus Models Estimating the Odds of Condom Use
All Events Partner Attends Same College Partner Not From Respondent's College All Events Partner Attends Same College Partner Not From Respondent's College
WomenMenEitherWomenMenEitherWomenMenEitherWomenMenEitherWomenMenEitherWomenEitherEither
Year of College
Freshman Year
Sophomore Year1.271.59*1.42**1.431.311.34^1.241.491.380.39***0.32**0.39***0.20***0.28*0.23***0.570.55^0.55^
Junior Year1.140.881.071.200.670.951.061.141.110.62^0.480.58*0.31*0.400.33**1.100.980.98
Senior Year1.55**1.78*1.65***1.49^1.361.39^1.59^2.20^1.81**0.54*0.38*0.49**0.25**0.28^0.25***0.980.900.90
Mother's Educational Attainment
Mother Received a High School Education or Less
Mother Received Some College Education0.850.740.83^0.980.700.880.720.740.74^0.890.46^0.740.540.30^0.45*0.940.920.92
Mother Received a Bachelor's Degree0.900.780.850.970.730.870.851.050.910.700.700.69^0.33**0.690.39**0.980.910.91
Mother Received a Graduate Degree0.860.58**0.76*0.920.52*0.77^0.850.860.870.56*0.32**0.48***0.27**0.22*0.25***0.690.660.66
Year of College × Mother's Educational Attainment
Sophomore × Some College0.981.101.000.801.490.991.160.851.051.372.89^1.67^1.603.65^2.091.811.791.79
Junior × Some College1.201.91*1.35^0.992.87*1.421.501.281.420.912.171.171.462.991.950.810.890.89
Senior × Some College1.061.131.050.991.111.001.141.751.160.941.631.081.562.091.740.810.800.80
Sophomore × Bachelor's Degree0.70^0.990.790.61*1.220.790.810.690.781.511.981.72*2.50^1.452.33*1.381.811.81
Junior × Bachelor's Degree1.031.87*1.241.022.55*1.411.081.031.091.031.141.101.480.991.480.830.960.96
Senior × Bachelor's Degree0.931.381.051.021.421.150.881.110.921.301.321.352.45^1.022.07^0.911.041.04
Sophomore × Graduate Degree0.831.070.890.771.480.960.820.630.742.33*3.86*2.66**3.16*5.07*3.71**3.03*2.77*2.77*
Junior × Graduate Degree1.301.641.341.222.93**1.62*1.300.510.981.372.541.631.974.36^2.67*1.281.141.14
Senior × Graduate Degree1.091.80^1.241.002.27*1.321.200.781.042.32*2.69^2.44**4.21*2.713.69**1.862.05^2.05^
School Gender Composition
≤ 53% Female
≥ 53% Female0.83*1.091.050.841.110.79*0.960.950.921.051.121.050.851.360.931.401.191.19
≥ 53% Female × Sophomore1.30^0.851.111.280.881.141.211.101.131.420.841.151.96*0.721.440.920.910.91
≥ 53% Female × Junior1.73***1.161.50***1.73**1.151.53**1.56^1.271.49*1.150.690.971.96^0.491.280.690.750.75
≥ 53% Female × Senior1.61**0.851.30*1.65*1.181.53**1.360.731.140.831.070.871.141.181.210.56^0.61^0.61^
Observations71443131102754294210764012778967374525821252383413757842159119916471647
Supplemental Table D3. Odds Ratios for Equation 3 Reestimated Without Controls
Models Estimating the Odds of Coitus Models Estimating the Odds of Condom Use
All Events Partner Attends Same College Partner Not From Respondent's College All Events Partner Attends Same College Partner Not From Respondent's College
WomenMenWomenMenWomenMenWomenMenWomenMenWomenMen
During/After Freshman Year
First Year of College
Years 2/3/4 of College1.29*1.361.271.091.281.550.50**0.37*0.24***0.30*0.860.53
Mother's Educational Attainment
Mother Received a High School Education or Less
Mother Received Some College Education0.850.740.990.700.720.740.890.46^0.540.30^0.940.77
Mother Received a Bachelor's Degree0.890.780.970.730.851.050.700.700.33**0.690.980.67
Mother Received a Graduate Degree0.840.58**0.920.52*0.850.860.56*0.32**0.27**0.22*0.690.52
Grade × Mother's Educational Attainment
Years 2/3/4 × Some College1.061.300.921.641.261.091.062.28^1.573.011.031.44
Years 2/3/4 × Bachelor's Degree0.851.310.821.580.920.871.261.502.15^1.200.991.98
Years 2/3/4 × Graduate Degree1.041.430.972.06*1.060.641.96*3.09*3.12*4.03*1.901.94
School Gender Composition
≤ 53% Female
≥ 53% Female0.83*1.080.871.110.950.951.041.120.851.361.400.80
≥ 53% Female × Years 2/3/41.50***0.961.63***1.061.35^1.031.110.851.64^0.750.711.01
Observations714431314294210727789672582125213757841199448