============================================= DEPARTMENT OF BIOSTATISTICS CONSULTING CLINIC MONDAY, APRIL 30, 2007 CLIENT: STEPHANIE VAUGHN ============================================= WILCOXON RANK-SUM TEST COMPARING BPD TO NON-BPD BPD=0 IF NON-BPD BPD=1 IF BPD Two-sample Wilcoxon rank-sum (Mann-Whitney) test bpd | obs rank sum expected -------------+--------------------------------- 0 | 50 2145.5 2525 1 | 50 2904.5 2525 -------------+--------------------------------- combined | 100 5050 5050 unadjusted variance 21041.67 adjustment for ties -1374.87 ---------- adjusted variance 19666.79 Ho: num_cr~s(bpd==0) = num_cr~s(bpd==1) z = -2.706 Prob > |z| = 0.0068 SUMMARY STATISTICS OF YEARS IN SYSTEM BY BPD STATUS -> bpd = 0 in_system ------------------------------------------------------------- Percentiles Smallest 1% 1 1 5% 1 1 10% 1 1 Obs 50 25% 1 1 Sum of Wgt. 50 50% 2 Mean 2.9 Largest Std. Dev. 2.02535 75% 5 7 90% 6 7 Variance 4.102041 95% 7 7 Skewness .9245572 99% 8 8 Kurtosis 2.630319 ---------------------------------------------------------------------------------------- -> bpd = 1 in_system ------------------------------------------------------------- Percentiles Smallest 1% 1 1 5% 1 1 10% 1 1 Obs 50 25% 2 1 Sum of Wgt. 50 50% 3.5 Mean 4.3 Largest Std. Dev. 2.812146 75% 6 10 90% 8.5 10 Variance 7.908163 95% 10 10 Skewness .7343192 99% 11 11 Kurtosis 2.534282 SUMMARY STATISTICS OF AGE BY BPD STATUS -> bpd = 0 age ------------------------------------------------------------- Percentiles Smallest 1% 18 18 5% 19 18 10% 19.5 19 Obs 50 25% 27 19 Sum of Wgt. 50 50% 35.5 Mean 37.18 Largest Std. Dev. 13.41594 75% 47 58 90% 56.5 59 Variance 179.9873 95% 59 60 Skewness .4224349 99% 71 71 Kurtosis 2.329499 ---------------------------------------------------------------------------------------- -> bpd = 1 age ------------------------------------------------------------- Percentiles Smallest 1% 17.5 17.5 5% 18 18 10% 19 18 Obs 50 25% 23 19 Sum of Wgt. 50 50% 30 Mean 32.81 Largest Std. Dev. 11.79454 75% 41 52 90% 50 55 Variance 139.1111 95% 55 60 Skewness .6619003 99% 61 61 Kurtosis 2.48303 SUMMARY STATISTICS OF NUMBER OF CRISIS CALLS BY BPD STATUS -> bpd = 0 num_crisis_calls ------------------------------------------------------------- Percentiles Smallest 1% 0 0 5% 0 0 10% 0 0 Obs 50 25% 0 0 Sum of Wgt. 50 50% 1 Mean 1.26 Largest Std. Dev. 1.258603 75% 2 4 90% 3 4 Variance 1.584082 95% 4 4 Skewness 1.050322 99% 5 5 Kurtosis 3.615419 ---------------------------------------------------------------------------------------- -> bpd = 1 num_crisis_calls ------------------------------------------------------------- Percentiles Smallest 1% 0 0 5% 0 0 10% .5 0 Obs 50 25% 1 0 Sum of Wgt. 50 50% 2 Mean 1.92 Largest Std. Dev. 1.35285 75% 3 4 90% 4 5 Variance 1.830204 95% 5 5 Skewness .9454186 99% 6 6 Kurtosis 3.748148 UNADJUSTED PROPORTIONAL ODDS MODEL - RESULTS SIMILAR TO WILCOXON-RANK SUM TEST Ordered logistic regression Number of obs = 100 LR chi2(1) = 7.58 Prob > chi2 = 0.0059 Log likelihood = -155.3515 Pseudo R2 = 0.0238 ------------------------------------------------------------------------------ num_crisis~s | Odds Ratio Std. Err. z P>|z| [95% Conf. Interval] -------------+---------------------------------------------------------------- bpd | 2.743973 1.021547 2.71 0.007 1.322781 5.692088 -------------+---------------------------------------------------------------- /cut1 | -.8754604 .2936639 -1.451031 -.2998896 /cut2 | .7440501 .2899405 .1757772 1.312323 /cut3 | 1.982605 .343493 1.309371 2.655839 /cut4 | 2.807077 .4123604 1.998865 3.615288 /cut5 | 3.792901 .5664846 2.682612 4.903191 /cut6 | 5.217404 1.035457 3.187944 7.246863 ------------------------------------------------------------------------------ ADJUSTED PROPORTIONAL ODDS MODEL - ADJUSTING FOR AGE AND YEARS IN SYSTEM Ordered logistic regression Number of obs = 100 LR chi2(3) = 13.19 Prob > chi2 = 0.0042 Log likelihood = -152.54764 Pseudo R2 = 0.0414 ------------------------------------------------------------------------------ num_crisis~s | Odds Ratio Std. Err. z P>|z| [95% Conf. Interval] -------------+---------------------------------------------------------------- bpd | 2.226592 .8996821 1.98 0.048 1.008561 4.91563 age | 1.007531 .0153732 0.49 0.623 .9778464 1.038117 in_system | 1.179932 .0935563 2.09 0.037 1.010103 1.378315 -------------+---------------------------------------------------------------- /cut1 | -.1875423 .613303 -1.389594 1.01451 /cut2 | 1.465904 .6225289 .2457702 2.686039 /cut3 | 2.785856 .6709297 1.470858 4.100854 /cut4 | 3.655636 .7211037 2.242299 5.068973 /cut5 | 4.667113 .8228923 3.054274 6.279952 /cut6 | 6.113248 1.19956 3.762153 8.464343 ------------------------------------------------------------------------------