Appendix Table 2 – untransformed model coefficients

Variable Coefficient
constant -6.1304
Sex – male 0.6507
Age (per year) -0.008548
Previous violent crime -0.2427
Previous drug use 0.0817
Previous alcohol use 0.2541
Previous self-harm 0.9359
Educational level

Upper secondary

Post-secondary

 

0.2133

0.5217

Parental drug or alcohol use -0.3549
Parental suicide 0.5618
Recent treatment – antipsychotic 0.2533
Recent treatment – antidepressant 0.5624
Inpatient diagnosis 1.0829
Length of first inpatient stay > 7 days 0.2047
Number of episodes > 7 -0.2562
Benefit receipt -0.1920
Parental psychiatric hospitalisation 0.1816
Comorbid depression 0.2362

To calculate predicted probability for an individual:

1) Calculate X. We illustrate the equation for X for the first three variables, however all 17 need to be included using the coefficients from the table above.

X = -6.1304 + 0.6507*Male – 0.008548*Age – 0.2427*Previous violent crime + …

2) Calculate predicted probability = 1 / [1 + exp(-X)]

3) If predicted probability > 1%, individual is classified at high risk; otherwise individual is classified at low risk