CHRNA3 and chronic obstructive pulmonary disease: Post hoc power analysis (two-proportion approximation, α = 0.05) indicated moderate power to detect the observed differences for CHRNA3 rs8034191 vs. tobacco intake (power ≈ 0.63) and EPHX1 rs2234922 vs. COPD (power ≈ 0.56), whereas power was limited for smaller effects.