Study of adolescents with ADHD. Children with attentiondeficit/

hyperactivity disorder (ADHD) were monitored to evaluate their risk for substance (e.g., alcohol, tobacco, illegal drug) use (Journal of Abnormal Psychology, Aug. 2003).

The following data were collected on 142 adolescents diagnosed with ADHD:

y = frequency of marijuana use the past six months x1 = severity of inattention 15@point scale2 x2 = severity of impulsivity-hyperactivity15@point scale2 x3 = level of oppositional@defiant and conduct disorder 15@point scale2

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: b1 = 0 resulted in a p-value less than

.01. Interpret this result.

e. The t-test for H0: b2 = 0 resulted in a p-value greater than .05. Interpret this result.

f. The t-test for H0: b3 = 0 resulted in a p-value greater than .05. Interpret this result.