Despite these limitations, there are unique and compelling features of the Swedish register data. Its comprehensive nature ensures findings represent the entire Swedish population, and the population size enables us to detect predictive factors of modest effect. Furthermore, we do not rely on self-reports, reducing error due to recall bias or sincere misconceptions about one’s own behavior. Sweden’s socialized health care system increases the likelihood that individuals with drug or alcohol problems receive medical care (and are thus appropriately included in the current analyses) whereas in countries with less egalitarian systems those individuals would potentially be excluded from care as a function of income/resources.
