G2: Often used to denote deviance.
Galbraith plot: A graphical method for identifying outliers in a meta―analysis. The standardized effect size is plotted against precision (the reciprocal of the standard error). If the studies are homogeneous, then they should be distributed within +/−2 standard errors of the regression line through the origin. An example is given in Figure 42. [Ader, H. J. andMellenberg, G. J., 1999, ResearchMethodology, Sage, London.]
GAM: Abbreviation for geographical analysis machine and for generalized additive model.
Gambler's fallacy: The belief that if an event has not happened for a long time, then it is bound to occur soon. [Everitt, B. S., 1999, Chance Rules, Springer, New York.]
Game theory: The branch of mathematics that deals with the theory of contests between two or more players under specified sets of rules. The subject assumes a statistical aspect when part of the game proceeds under a chance scheme. [International Journal of Game Theory, 1979, 8, 175–92.]
Gamma distribution: A probability distribution of which the shape depends on two parameters. Some examples are given in Figure 43. Often used to model heavily skewed data. [Evans, M., Hastings, N. and Peacock, B., 2000, Statistical Distributions, 3rd edn, J.Wiley & Sons, New York.]
Garbage in, garbage out (GIGO): A term that draws attention to the fact that sensible output follows only from sensible input. Specifically, if the data are originally of dubious quality, then so will be the results.