Casual Contraception in Casual Sex
Sensitivity of the Demographic Trends to Age at Onset, Hookup Ordinality and Partner Count

Table 1. Sensitivity of the Demographic Trend to Age at Onset and Hookup Ordinality
Models Estimating the Odds of Coitus Models Estimating the Odds of Condom Use
Eq 2 Eq 2 + Onset Eq 2 + Order Eq 2 + Cumulative Partners Eq 2 Eq 2 + Onset Eq 2 + Order Eq 2 + Cumulative Partners
WomenMenWomenMenWomenMenWomenMenWomenMenWomenMenWomenMenWomenMen
Year of College
Freshman Year
Sophomore Year1.29***1.53***1.23**1.48***1.29***1.33**1.031.22^0.68**0.62*0.65***0.61**0.67**0.64*0.69**0.62**
Junior Year1.79***1.53***1.55***1.46**1.76***1.36**1.23*1.080.72**0.63*0.68**0.61*0.72**0.66*0.74*0.63*
Senior Year2.09***2.27***1.71***2.11***1.95***2.03***1.18*1.29*0.63***0.62*0.59***0.58**0.65***0.63*0.65***0.63*
Mother's Educational Attainment
Mother Received a High School Education or Less
Mother Received Some College Education0.85*0.870.87^0.870.85*0.860.890.860.920.900.910.880.930.960.920.90
Mother Received a Bachelor's Degree0.80**0.940.83*0.910.79**0.930.87^0.960.861.030.841.020.871.130.851.03
Mother Received a Graduate Degree0.84*0.73*0.81*0.64***0.83*0.71**0.83*0.67**0.890.800.870.810.890.890.890.80
Population Density During High School
Rural0.981.44*0.951.44^1.061.49*0.921.51*0.900.860.910.830.880.750.900.87
Small Town1.25**1.031.22**1.071.29***1.021.25**1.041.120.901.130.881.120.891.120.91
Suburban
Medium City1.13^1.061.14^1.031.15^1.081.20*1.011.23^0.881.25^0.871.22^0.891.23^0.88
Large City1.32**1.26^1.31**1.141.30**1.211.24*1.111.29^1.371.29^1.361.33^1.361.29^1.36
Respondent's Race
White
Black1.021.051.250.931.061.041.160.890.962.63*0.972.71**0.932.51*0.952.67**
Hispanic0.77**1.000.82^0.930.83^1.060.900.941.321.161.291.191.251.121.311.16
Asian0.900.72^1.030.901.010.781.140.890.991.190.961.150.961.070.981.17
Other Race0.811.010.920.920.891.010.921.081.240.971.230.991.140.871.220.98
Mixed Race1.121.181.021.141.121.110.911.061.131.101.151.131.131.161.141.11
Partner's Race
White
Black1.39**0.961.31*0.881.40**0.981.220.851.77**0.731.85**0.771.75**0.691.78**0.74
Hispanic0.950.860.880.840.980.810.940.850.940.870.980.850.930.940.930.87
Asian0.890.76^0.920.810.940.74^1.020.840.821.200.791.180.801.190.801.19
Mixed Race1.25*1.031.19^0.861.23*0.921.31*0.920.911.110.931.120.921.090.901.13
Other or Not Indicated0.68*0.780.750.760.72^0.720.72^0.850.681.220.721.190.701.370.681.20
Childhood Religion
Catholic0.84*0.960.961.170.83*0.970.971.080.921.53*0.881.51*0.921.55*0.911.54*
Jewish0.77*0.900.80^1.160.72**0.850.830.971.301.431.291.421.361.491.301.45
Other Religion0.931.091.061.39*0.941.181.041.260.841.050.811.030.841.010.841.05
Protestant0.79**0.910.901.220.82*0.970.911.051.241.331.181.291.211.301.241.34
None
Prior Hookups With This Partner
No Prior Hookups
1-2 Prior Hookups1.57***1.45***1.131.75*
3-5 Prior Hookups2.22***2.34***1.021.43
≥ 6 Prior Hookups4.83***3.82***0.58***0.46***
Age At First Intercourse
15 Or Younger1.57***2.12***0.61***0.75
16 Years Old1.16^1.71***0.860.67*
17 Years Old
18 Years Old0.931.081.040.92
19 Or Older0.58***0.72*1.101.18
Not Applicable0.02***0.07***1.000.69
Cumulative Intercourse Partners
Zero to 1
2 to 36.11***4.14***1.021.26
4 or more14.37***10.62***0.871.07
Immigrant0.980.971.021.060.991.080.970.941.041.431.011.451.031.331.031.44
Observations7144313171443131714431317144313125821252258212522582125225821252
Table 2. Sensitivity of the Demographic Trend to Age at Onset and Hookup Ordinality, When Hooking Up With a Partner From the Same College
Models Estimating the Odds of Coitus Models Estimating the Odds of Condom Use
Eq 2 Eq 2 + Onset Eq 2 + Order Eq 2 + Cumulative Partners Eq 2 Eq 2 + Onset Eq 2 + Order Eq 2 + Cumulative Partners
WomenMenWomenMenWomenMenWomenMenWomenMenWomenMenWomenMenWomenMen
Year of College
Freshman Year
Sophomore Year1.121.59***1.141.53**1.19^1.36*0.971.27^0.56***0.60*0.53***0.59*0.54***0.64^0.58**0.60^
Junior Year1.57***1.64***1.54***1.62**1.54***1.40*1.24*1.220.69*0.59^0.64*0.57*0.70*0.670.71^0.59^
Senior Year1.74***2.15***1.60***2.07***1.69***1.86***1.091.260.60**0.51*0.56**0.48**0.62**0.55*0.64*0.52*
Mother's Educational Attainment
Mother Received a High School Education or Less
Mother Received Some College Education0.910.960.910.940.940.970.940.950.800.770.790.750.780.790.820.77
Mother Received a Bachelor's Degree0.870.970.900.940.900.980.910.970.63*0.830.61**0.820.62*0.860.63*0.83
Mother Received a Graduate Degree0.870.860.870.76^0.880.820.920.770.62*0.650.59*0.660.61*0.720.61*0.65
Population Density During High School
Rural1.201.49^1.201.391.251.47^1.081.63*0.970.660.950.640.950.620.970.65
Small Town1.23*1.061.161.081.19^1.061.131.081.291.011.31^0.981.291.041.291.00
Suburban
Medium City1.20*1.131.19^1.061.20^1.131.22^1.091.37^0.731.39^0.731.37^0.761.37^0.74
Large City1.30*1.46*1.37*1.41*1.30*1.42*1.25^1.42*1.70*1.401.67*1.401.80**1.491.68*1.40
Respondent's Race
White
Black1.121.061.300.881.071.021.200.810.861.950.861.990.861.850.841.96
Hispanic0.940.950.940.831.041.021.080.891.542.27^1.512.33^1.451.821.492.28^
Asian1.050.721.280.911.150.771.46*0.940.970.970.920.910.940.840.940.97
Other Race1.020.871.160.751.090.831.231.001.420.521.470.531.310.481.380.52
Mixed Race1.121.29^0.941.251.151.200.82^1.141.231.141.281.141.161.171.261.15
Partner's Race
White
Black1.250.901.210.881.230.971.120.871.370.761.470.791.400.681.370.76
Hispanic0.890.850.760.890.900.820.850.930.911.211.011.260.961.200.911.21
Asian0.770.800.770.870.820.770.820.890.951.220.961.190.951.160.931.21
Mixed Race1.081.120.910.921.031.001.091.000.901.150.971.170.951.160.901.15
Other or Not Indicated0.820.870.910.860.790.850.840.920.44*1.750.45^1.760.45^1.930.47^1.74
Childhood Religion
Catholic0.79*0.930.951.140.78**0.940.961.110.841.300.811.280.861.300.831.31
Jewish0.79^0.870.851.110.75*0.800.880.971.191.031.181.001.271.051.191.04
Other Religion0.841.041.031.310.881.130.981.220.841.730.821.730.851.580.841.74
Protestant0.78*0.850.951.110.81^0.890.950.981.300.911.240.871.280.881.290.91
None
Prior Hookups With This Partner
No Prior Hookups
1-2 Prior Hookups1.54***1.35*0.911.62
3-5 Prior Hookups2.40***2.55***0.881.19
≥ 6 Prior Hookups4.97***3.31***0.46***0.45***
Age At First Intercourse
15 Or Younger1.68***2.65***0.59**0.90
16 Years Old1.081.92***0.900.94
17 Years Old
18 Years Old0.941.251.060.95
19 Or Older0.53***0.821.151.51
Not Applicable0.02***0.10***4.070.96
Cumulative Intercourse Partners
Zero to 1
2 to 36.58***4.80***1.040.95
4 or more16.14***11.93***0.720.93
Immigrant0.881.010.901.090.861.100.850.981.281.041.271.041.310.981.251.05
Observations429421074294210742942107429421071375784137578413757841375784
Table 3. Sensitivity of the Demographic Trend to Age at Onset and Hookup Ordinality, When Hooking Up With a Partner Who Does Not Attend the Same College
Models Estimating the Odds of Coitus Models Estimating the Odds of Condom Use
Eq 2 Eq 2 + Onset Eq 2 + Order Eq 2 + Cumulative Partners Eq 2 Eq 2 + Onset Eq 2 + Order Eq 2 + Cumulative Partners
WomenMenWomenMenWomenMenWomenMenWomenMenWomenMenWomenMenWomenMen
Year of College
Freshman Year
Sophomore Year1.31*1.241.32*1.281.31*1.121.080.950.860.680.830.680.850.670.860.67
Junior Year1.68***1.271.45**1.151.80***1.281.090.750.820.740.800.720.800.630.820.75
Senior Year2.00***2.31***1.75***2.26***1.98***2.32***1.161.190.73^0.910.69*0.840.75^0.780.73^0.93
Mother's Educational Attainment
Mother Received a High School Education or Less
Mother Received Some College Education0.78*0.810.830.830.75*0.760.840.820.940.980.930.890.961.140.940.97
Mother Received a Bachelor's Degree0.74**0.950.77*1.030.70**0.920.861.130.981.020.951.000.991.220.981.02
Mother Received a Graduate Degree0.80^0.62*0.74*0.54**0.77*0.60*0.75*0.59*1.110.741.120.701.090.841.110.75
Population Density During High School
Rural0.841.470.72^1.450.901.77^0.771.310.741.270.761.320.730.980.741.29
Small Town1.35**1.021.31*1.061.41**0.931.43**1.000.980.621.000.59^0.980.620.980.62
Suburban
Medium City1.060.871.040.901.080.921.140.811.071.011.101.001.071.081.071.01
Large City1.230.931.190.811.210.861.150.710.961.010.941.030.960.890.960.97
Respondent's Race
White
Black0.830.991.031.220.901.020.951.041.134.39^1.164.28^1.134.58*1.134.37^
Hispanic0.59***1.170.64**1.190.60**1.170.68*1.071.060.981.080.981.031.081.060.95
Asian0.69^0.800.64*1.050.780.880.710.960.811.960.822.020.792.040.811.99
Other Race0.58*1.310.57*1.250.62*1.410.53*1.140.973.47*0.943.40*0.862.93^0.973.47*
Mixed Race1.120.991.120.951.050.901.020.951.010.921.020.931.081.131.020.95
Partner's Race
White
Black1.66**1.331.58*0.881.71**1.231.46^0.762.18**0.902.24**1.212.07**0.772.19**0.97
Hispanic0.940.740.920.701.000.730.950.721.130.651.150.671.110.631.130.67
Asian1.010.61^1.230.671.070.621.400.690.921.220.841.310.901.200.921.18
Mixed Race1.55**0.891.73**0.791.56**0.791.63**0.771.031.031.021.081.010.861.031.07
Other or Not Indicated0.660.730.670.800.730.620.701.001.120.661.170.611.210.671.120.64
Childhood Religion
Catholic0.860.960.931.110.871.010.931.001.052.09*1.002.05*1.032.18*1.052.13*
Jewish0.69*1.040.751.230.67*1.140.731.081.344.03**1.393.61*1.404.35**1.344.07**
Other Religion1.011.041.121.431.021.161.131.240.910.640.870.600.890.580.900.65
Protestant0.71*1.010.821.460.76^1.170.831.201.172.20*1.142.15*1.132.13*1.172.20*
None
Prior Hookups With This Partner
No Prior Hookups
1-2 Prior Hookups1.64***1.46*1.332.46*
3-5 Prior Hookups2.04***2.02**1.052.07^
≥ 6 Prior Hookups4.59***4.69***0.66**0.53*
Age At First Intercourse
15 Or Younger1.50**1.51^0.63*0.52^
16 Years Old1.29^1.340.880.45*
17 Years Old
18 Years Old0.890.811.070.88
19 Or Older0.65**0.51*1.050.91
Not Applicable0.02***0.03***0.440.36
Cumulative Intercourse Partners
Zero to 1
2 to 35.88***3.56***1.041.39
4 or more13.64***10.96***1.021.03
Immigrant1.070.911.140.951.131.061.100.870.982.17^0.922.24^0.952.110.982.22^
Observations27789672778967277896727789671199448119944811994481199448