Dalam ilmu statistika, sebuah pencilan adalah titik data yang terpaut jauh dari titik data lainnya.[1][2] Pencilan kemungkinan dapat berasal dari variabilitas pengukuran atau galat percobaan. Pencilan akibat galat sering kali diabaikan.[3] Pencilan dapat mengakibatkan masalah serius dalam analisis statistik.
^Grubbs, F. E. (February 1969). "Procedures for detecting outlying observations in samples". Technometrics. 11 (1): 1–21. doi:10.1080/00401706.1969.10490657. An outlying observation, or "outlier," is one that appears to deviate markedly from other members of the sample in which it occurs.
^Grubbs 1969, hlm. 1 mengatakan "An outlying observation may be merely an extreme manifestation of the random variability inherent in the data. ... On the other hand, an outlying observation may be the result of gross deviation from prescribed experimental procedure or an error in calculating or recording the numerical value."