Results indicated a trend toward rate of metabolism predicting mean puff volume in the total sample, however, after controlling for HC use, this trend became significant (t = 2.126, p = .037, adjusted R2 = .067) with higher metabolism predicting higher mean puff volume. Metabolism also showed a trend toward inversely predicting number of puffs in the overall sample (t = −1.763, p = 0.82, adjusted R2 = .024). There were no significant relationships between metabolism and mean puff duration, interval, velocity, or total puff volume (Figure 1. displays scatter plots and regression lines for the total sample). When the sample was stratified by sex, significant findings occurred only among males: metabolism positively predicted mean puff volume (t = 2.812, p = .009, adjusted R2 = .192), and inversely predicted both number of puffs (t = −3.160, p=0.004, adjusted R2 = .237) and mean puff duration (t = −2.064, p = .048, adjusted R2 = .101). The regression scatter plots are shown in Figure 2. Among boys, metabolism accounted for 19.2% of the variability in mean puff volume; metabolism and
