The lessening in force of a phenomenon or interaction with increasing distance from the location of maximum intensity; the inverse distance effect. Seidl et al. (2006) BMC Health Serv. Rev. 6, 13 find an inverse relationship between the geographical distance from a patient’s home to a clinic, and the likelihood of the patient actually turning up there. Gimpel et al. (2008) Pol. Geog. 27, 2 find that technology has lessened, but not eradicated, the friction of distance. See Farhan and Murray (2006) Annals Reg. Sci. 40, 2.