This work documents the history of techniques that statisticians use to manipulate economic, meteorological, biological, and physical data taken from observations recorded over time. The decomposition tools include index numbers, moving averages, relative time frameworks, and the use of differences (i.e., subtracting one observation from the previous value in the series). This history is accessible to students with a basic knowledge of statistics, as well as financial analysts, statisticians, and historians of economic thought and science.