title: Statistics notebook: entry II.B: Observational study, (1) retrospective study, and (2) prospective study.
authors.affiliation: Department of Mathematics, California State University, Fullerton 92634.
authors.forename: P N
authors.initials: PN
authors.lastname: de Land
authors.forename: W W
authors.initials: WW
authors.lastname: Chase
mesh_terms: D006801:Humans; D011446:Prospective Studies; D012107:Research Design / Q000706:statistics & numerical data*; D012189:Retrospective Studies