Is the proposed explanatory fac-
tor correlated with trust and civic
engagement? If not, it is difficult to
see why that factor should even be
placed in the lineup. For example,
many women have entered the paid
labor force during the period in
question, but if working women
turned out to be more engaged in
community life than housewives, it
would be harder to attribute the
downturn in community organiza-
tions to the rise of two-career
families.
Is the correlation spurious? If
parents, for example, were more
likely to be joiners than childless
people, that might be an important
clue. However, if the correlation
between parental status and civic
engagement turned out to be en-
tirely spurious, due to the effects of
(say) age, we would have to re-
move the declining birth rate from
our list of suspects