TABLE 2

Summary of Moderator Analyses for Sleep Latency

CharacteristickbQ RegressionQ Residual
Methodologic/design characteristics
 Length of time on medication (in days)70.005Q(1) = 0.76, P = .38Q(5) = 6.43, P = .27
 Mean total dosage/d (in milligrams)4−0.01Q(1) = 3.82, P = .051Q(2) = 1.75, P = .42
 Frequency of dosage/d50.42**Q(1) = 10.24, P = .001Q(3) = 5.56, P = .13
 Frequency of dosage/wk50.02Q(1) = 0.04, P = .85Q(3) = 3.77, P = .29
 No. of nights of sleep assessed70.01Q(1) = 2.01, P = .16Q(5) = 5.72, P = .34
 Method of sleep latency assessment7−0.17Q(1) = 0.62, P = .043Q(5) = 5.52, P = .36
 Stimulant medication class7−0.29Q(1) = 1.29, P = .25Q(5) = 5.44, P = .36
 Funding source70.04Q(1) = 0.03, P = .86Q(5) = 6.08, P = .30
Sample characteristics
 Gender60.005Q(1) = 0.36, P = .55Q(4) = 5.26, P = .26
 Age7−0.007Q(1) = 0.26, P = .61Q(5) = 5.59, P = .35
  • b, unstandardized regression coefficient; k, number of studies; Q Regression, homogeneity test for regression (ie, regression sum of squares); Q Residual, sum-of-squares residual (represents sampling error and random variation). **P < .01.