Burdorf A. The complexity of cohort studies for everyday ailments. Huisarts Wet 2015;58(6):302-4. Cohort studies are essential to medical science. The classic cohort studies of the last 50 years are still relevant, if only for the huge amount of data generated. However, cohort studies are not automatically appropriate for everyday medical ailments. Because of the complex patterns of cause and effect in these ailments, investigators need to be inventive and use alternative methods for statistical analysis.