because the prevalence of disorders was only slightly changed across substances when clustering was required. Lastly, several of the confidence intervals in Table 5 are substantial. We believe this is a result of the low prevalence rates of SUDs in Wave 1 resulting in a small cell sizes in the odds-ratio analyses. Despite these instances, many of the odds-ratios are significantly greater than one, with small confidence intervals; we can be confident in the significance of these results, but less certain about the upper limit of the true odds-ratio.
