Study of adolescents with ADHD. Children with attention-deficit/hyperactivity disorder (ADHD) were monitored to evaluate their risk for substance (e.g., alcohol, tobacco, illegal drug) use (Journal of Abnormal Psychology, August 2003). The following data were collected on 142 adolescents diagnosed with ADHD:
y = frequency of marijuana use the past 6 months
x1 = severity of inattention (5-point scale)
x2 = severity of impulsivity-hyperactivity (5-point scale)
x3 = level of oppositional-defiant and conduct disorder (5-point scale)
(a) Write the equation of a first-order model for E(y).
(b) The coefficient of determination for the model is R2 = .08. Interpret this value.
(c) The global F-test for the model yielded a p-value less than .01. Interpret this result.
(d) The t-test for H0: β1 = 0 resulted in a p-value less than .01. Interpret this result.
(e) The t-test for H0: β2 = 0 resulted in a p-value greater than .05. Interpret this result.
(f) The t-test for H0: β3 = 0 resulted in a p-value greater than .05. Interpret this result.