THE DECOMPOSITION OF INCOME INEQUALITY: AN ANALYSIS BASED ON THE NORTHERN IRELAND FAMILY EXPENDITURE SURVEY FOR 1985

This paper conducts an empirical investigation into the issue of inequality decomposition, using the 1985 FES micro data tapes for Northern Ireland. It is hoped that it makes three contributions. First, by using the raw data, it permits a fairly rich disaggregation of individuals. The disaggregation employed in this paper viz. by individuals belonging to different'family types'and individuals of different'economic status'seems particularly relevant to social policy. Second the data also permits a disaggregation of total income by type of income: this permits one to assess, for example, how much of total inequality is caused by inequality in the distribution of income from different sources. Finally, the analysis is consistent with the existing theoretical literature on inequality decomposition.
The main results may be summarized briefly. When the FES sample was divided by subgroups of family type or economic status, then, in 1985, most of income inequality in NI was due to within group rather than to between group inequality. When total income was disaggregated by income type, then inequalities in the distribution of wages and salaries made the largest contribution to the inequality of total income. Prosperous families in NI tended to contain within them a far greater proportion of secondary workers than did the less well off families. It was not implausible therefore that the distribution of employment between families made a major contribution to wage inequalities between them.