Observe data collection at the moment of measurement See, observe, learn how data are collected at moment and place of measurement. "You never learn more about a process than when you directly observe how data are actually measured," said Cuthbert Daniel, a superb applied statistician. See with fresh eyes. Walk around what you want to learn about. Talk to those who do measurements. See how numbers came to be. Do those measuring know the desired answer? Are those measuring skilled, alert, honest, biased, incompetent, sloppy, tired and emotional?...Artifacts and errors in measurements measured? How are outliers adjudicated? Edward Tufte, Seeing With Fresh Eyes uxmeasurement
Wang tiles Wang tiles (Hao Wang, 1961) are a class of formal systems. They are modelled visually by square tiles with a color on each side. A set of such tiles is selected, and copies of the tiles are arranged side by side with matching colors, without rotating or reflecting them. The basic question about a set of Wang tiles is whether it can tile the plane or not, i.e., whether an entire infinite plane can be filled this way. The next question is whether this can be done in a periodic pattern. In 1966, Wang's student Robert Berger solved the problem in the negative. He proved that no algorithm for the problem can exist, by showing how to translate any Turing machine into a set of Wang tiles that tiles the plane if and only if the Turing machine does not halt. The undecidability of the halting problem then implies the undecidability of Wang's tiling problem. Wikipedia en.wikipedia.org Truchet TilesThe Tiling Patterns of Sebastien Truchet and the Topology of Structural Hierarchy mathalgorithms