Table 2

Treatment group differences: means, SDs, and t test results

Month 1 reportsMonth 4 reportsMonth 9 reports
Intervention group (n=283 dyads)Control group (n=296 dyads)Intervention group (n=253 dyads)Control group (n=276 dyads)Intervention group (n=249 dyads)Control group (n=279 dyads)
VariablesReporterMeanSDMeanSDtMeanSDMeanSDtMeanSDMeanSDt
*p<0.05; **p<0.01; ***p<0.001.
Communication about teen driving
    Driving discussionParent3.200.873.200.88NS2.760.962.520.942.90**2.350.902.170.582.35*
Teen2.890.932.730.902.10*2.371.022.180.992.14*1.950.821.800.792.14*
    Driving consequencesParent9.201.228.961.492.00*8.671.398.351.602.45*8.311.497.991.652.29*
Teen8.261.687.941.582.35*7.491.656.871.654.36***6.931.756.591.762.22*
Amount of teen driving
    Vehicle accessParent4.421.634.711.57−2.18*5.251.675.141.60NS5.481.565.621.48NS
    Restricted drivingParent8.621.068.221.154.28***7.631.227.471.30NS6.961.286.791.30NS
    Past month drivingTeen19.158.6419.388.34NS21.957.5522.467.26NS22.727.2123.327.34NS
    High risk drivingTeen3.583.024.113.03−2.11*5.523.455.653.21NS6.403.766.603.58NS
    TicketsTeen0.090.320.060.23NS0.140.360.150.38NS
    CrashesTeen0.180.400.230.46NS0.410.600.370.57NS
Limits on teen driving
    Teen passengersParent3.40.892.840.972.55*2.321.012.211.10NS1.930.931.791.04NS
Teen2.811.142.351.254.53***1.841.161.581.212.50*1.271.081.131.08NS
    High speed roadsParent2.351.121.991.273.62***1.851.141.551.133.06**1.371.081.211.12NS
Teen1.711.171.381.203.43**1.151.000.960.962.27*0.690.830.660.84NS
    Weekday night restrictionParent2.211.371.911.452.52*1.931.311.851.37NS1.431.281.341.25NS
Teen1.961.511.391.454.63***1.641.311.441.29NS1.081.221.051.16NS
    Weekend night restrictionParent1.651.431.211.413.72***0.570.890.470.94NS0.450.980.280.772.17*
Teen1.461.540.811.205.64***0.440.860.470.94NS0.260.730.240.69NS
    Driving limitsParent9.243.197.943.574.59***6.672.846.083.012.34*5.172.834.622.782.51*
Teen7.944.045.933.426.45***5.072.954.372.712.82**3.292.573.092.59NS