Theory of collective opinion shifts: from smooth trends to abrupt swings
E.S.P.C.I, 10 rue Vauquelin, 75005 Paris, France
2 Service de Physique de l'État Condensé, Orme des Merisiers, CEA Saclay, 91191 Gif sur Yvette Cedex, France and Science & Finance, Capital Fund Management, 6-8 Bd Haussmann, 75009 Paris, France
Corresponding author: a email@example.com
Published online: 21 September 2005
We unveil collective effects induced by imitation and social pressure by analyzing data from three different sources: birth rates, sales of cell phones and the drop of applause in concert halls. We interpret our results within the framework of the Random Field Ising Model, which is a threshold model for collective decisions accounting both for agent heterogeneity and social imitation. Changes of opinion can occur either abruptly or continuously, depending on the importance of herding effects. The main prediction of the model is a scaling relation between the height h of the speed of variation peak and its width w of the form , with for well connected populations. Our three sets of data are compatible with such a prediction, with for birth rates, for cell phones and for clapping. In this last case, we in fact observe that some clapping samples end discontinuously (w=0), as predicted by the model for strong enough imitation.
PACS: 02.50.-r – Probability theory, stochastic processes, and statistics / 87.23.-n – Ecology and evolution / 89.65.-s – Social and economic systems
© EDP Sciences, Società Italiana di Fisica, Springer-Verlag, 2005