Explaining union growth and decline with flows in and out of membership. An analysis of Swiss union locals

This paper enquires into the causes of union growth and decline by analysing flows in and out of membership. It does so at the level of 70 Swiss union locals over the period 2006-08. Gross flows in union membership are found to be much larger than the resulting net changes: turnover of annually 10 per cent thus is a surprisingly constant feature across unions. Net changes in membership are primarily determined by inflows: successful union locals differ from languishing ones with respect to their entry rates, whereas exit rates are similar. There is large variance in union locals’ entry rates that is not accounted for by the labour market context. Rather, it seems attributable to differences in union organization and strategy.