We established a set of inclusion and exclusion criteria to retain a variety of studies but also to permit some type of comparability across studies. First, all publications had to be peer-reviewed articles. Second, we attempted to include only studies that reported a sample size of at least 500 participants to avoid the most selective, convenient samples8. If few studies were found for a particular addictive behavior, however, we included studies with smaller sample sizes. Third, we focused our age range predominantly on adults of 18+ years of age to better capture prevalence of addictions from the start of emerging adulthood into middle/older adulthood. Fourth, we included only prevalence studies that examined both males and females, and removed studies with particularly selective samples (e.g., inpatients). Fifth, we focused on more recent studies of addictive behaviors (i.e. those since the DSM-IV was published in 1994), given the revisions to diagnostic criteria for addictions over the past several decades and the availability of recent large national studies that have examined ethnic differences in addictions.
