12 1966/67 in the former Western state, put the concentration coefficient (or Gini) at 0.47. Adeboye in a survey of 1635 households conducted in 1967 in all states except three, of the then Eastern Region, found a concentration ratio of 0.58. A number of scholars doing cross-national studies have presented various measures of inequality in Nigeria. Adelman and Morris (1971) presented data for Nigeria showing the richest 5 percent accounting for over 38 percent of income in Nigeria and the poorest 20 percent accounting for 7 percent of income in Nigeria. Odafalo (1981) gave the poorest 34 percent of taxpayers about 7 percent of income and concluded that the degree of inequality in Nigeria was widening.

There has been substantial inquiry into the pattern of income distribution in Nigeria. In an edited volume (Bienen and Diejomoah, 1981) many authors address this issue in detail using fragmented studies and national survey, a study which has attracted many criticisms. Bienen estimates that the national income inequality coefficient has moved from 0.5 in 1960 to 0.7 in 1975/76. He also speculates the worsening of it with the oil boom. There have been studies indicating the pattern of income distribution as far back as 1960 by Adelman and Morris (1971) and Vielrose (1963), although due to different methodologies and sample differences the figures do not compare very well. Anusionwu (1981) estimated income distribution by state using public sector employees for 1976 and gives Gini coefficients of 0.442 for Oyo, 0.494 for Niger, 0.496 for Bendel, 0.37 for Cross River and 0.524 for Sokoto. Most of the studies agree that rural inequality is similar to urban inequality. Aigbokhan (1988), who did the other major study on income distribution shows a decline in income inequality from 0.51 in 1960 to 0.37 in 1980 using consumer surveys. Studies by Collier (1983) and Bevan et al (1988) also provide estimates of changes in income composition and income inequality. Collier provides income inequality and land inequality in terms of different crop growers and regions, while Bevan _et al_ provide intrarural and inter-temporal income distribution.

Another issue of interest has been the general distribution of incomes between urban and rural areas. Bevan _et_ al(1988) indicated using nominal expenditure differentials, that between 1950 and 1980, there was a considerable expenditure differential in favor of urban residents because food was cheaper in the rural but manufactures were dearer. Between 1952 and 1954 per capita urban expenditure were 81 percent higher than rural per capita expenditures. It is worth noting that according to the present analysis, in 1985/86 urban per capita expenditures were only 32 percent higher than rural per capita expenditures, and in 1992/93 it was 13.5 percent higher. Faruqee (1993) argues that the gap which was in favor of urban areas at 58 percent in 1980/81 reduced to 8 percent in 1985/86 and reversed to be in favor of rural areas after 1986.

Most of the discussion on evolution of income (or expenditures) distribution included in here will focus on two surveys, the 1985/86 and 1992/93 National Consumer Survey. The first presentations in Table 4.1 below show the mean per capita expenditure distribution of households by expenditure deciles for 1985/86 and 1992/93. Table 4.1 shows that the bottom five percent had a large declining mean per capita expenditure from N 118.11 to N 70.24, between 1985/86 and 1992/93. The table also shows that households in the second five percent had average per capita expenditures of N 175.22 in 1985/86 and a mean expenditure of N 140.5 in 1992/93, a decline of almost 20 percent. The households in the third to tenth deciles show mean per capita expenditures increasing between the two periods from 5 percent in the third