Biology, and medicine in particular, have traditionally relied on single samples. This article discusses cosinor methods leading to reference standards, chronodesms, that allow one to continue to deal with single values, provided these values are cost-effectively time-specified. The methods proposed are intended for sparse and short time-series containing a rhythm that satisfies the assumption of sinusoidality. (41 ref) (PsycINFO Database Record (c) 2012 APA, all rights reserved)