Regression toward the mean of lymphocyte counts, categorized as lymphopenia (<1.1 × 10⁹/l), reference lymphocyte count (1.1–3.7 × 10⁹/l), and lymphocytosis (>3.7 × 10⁹/l) at the date of examination in 2003 in the Copenhagen General Population Study.

When categorizing lymphocyte counts, lymphopenia was defined as a lymphocyte count below the 2.5th percentile, the reference category was defined as a lymphocyte count between the 2.5th and 97.5th percentile, and lymphocytosis was defined as a lymphocyte count above the 97.5th percentile. Median values and interquartile ranges of 5,181 individuals at the 2003 examination (left) and the same individuals—maintaining the 2003 categorization—at the 2013 examination (right). Regression dilution ratio is 2.04/2.98 = 0.68. The table below the graph gives the percentage of individuals in each lymphocyte category at the 2003 examination (rows) and at the 2013 examination (columns).