Top panel: Distribution of quasar pairs across the complete redshift window of the SDSS DR16 quasar catalog. The highest concentration of pairs is found within the redshift range z ∈ [1.2, 2.8], totaling 2777 pairs. The catalog contains a total of 4011 pairs. Bottom panel: Distribution of quasar pairs detected within a cylindrical volume characterized by a projected radius of d_p ≤ 2 Mpc and a length of |ΔV| = 900 km/s. Black vertical lines denote $d_p^{\text{min}}\simeq 0.03\text{Mpc}$, representing the minimum projected separation at which a quasar pair can be reliably identified. This threshold is determined by the angular resolution of the SDSS camera, set at θ_SDSS = 5″, along with a mean redshift value of z_mean = 2.4.