The main reason for judging that the assumption is reasonable lies in the distribution
of union recognition. Union recognition has developed over a long period
and has a marked structural differentiation. As is well known, union recognition is
highly concentrated in large workplaces, in the public sector, in certain industries,
and in workplaces that are part of multi-site organisations. History has also played
a large part in shaping union recognition. Disney et al. (1995), Machin (2000) and
Millward et al. (2000) have shown that older workplaces are much more likely to be
unionised than those that have been set up in the past two decades. Indeed, whatever
the sector, industry or size of workplace, newer workplaces have been less likely
to unionise than older workplaces. Whatever the reasons for this historical difference
(discussed in Disney et al., 1995), information about the date at which work-places were set up contributes greatly to predicting whether unions are currently recognised