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ESRC Data Archive Bulletin:
Income and Wealth Distribution Data
Text: Tom Stark ... Page Compiled: Fionnuala McKenna
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Northern Ireland - Income
and Wealth Distribution Data
University of Ulster
In the United kingdom there are eight sources
for data on the distribution of income and wealth. These are:
- The Surveys of Personal Incomes by the Inland Revenue (SPI)
(Archive study number 2561)
- The CSO. Distributions, formerly known as the "Blue
- The Family Expenditure Survey (FES) (Archive study number
- The Effects of Benefits and Taxes data
- Households Below Average Income Data
- The New Earnings Survey (Archive study number 33186)
- The General Household Survey (GHS) (Archive study number 33090)
- The Distribution of Personal Wealth by the Inland Revenue
The SPI is produced annually and does contain
regional information. We shall examine this source below (See
section on SPI). The so called "Blue Book" distributions
are an extension of the SPI beyond the tax net. The last estimations,
done in 1988, refer to 1985/86. There is no indication that this
data is to be continued. It never did, however, contain any regional
The Family Expenditure Survey does have a
Northern Ireland dimension (see McGregor and Mckee in this issue).
The two following sources above are extensions of the FES. They
do not present regional break-down and there are no separate Northern
Ireland equivalent publications.
The New Earnings Survey relates to Great Britain.
There is, however, a separate Northern Ireland Survey (2211).
The General Household Survey also is confined to Great Britain.
Its Northern Ireland equivalent is the Continuous Household Survey
(CHS), discussed by Miller in this issue. Though both these sources
contain some income data, the method of collection - namely general
recall at an interview -means that it is unreliable for income
distribution analysis. For this reason we shall exclude this source
from our survey.
Finally there have never been any separate
official personal wealth distribution data for Northern Ireland.
The Inland Revenue has produced annual personal wealth distributions
since 1962. Initially the data referred to Great Britain. However,
after the major changes in estimation in 1976 the data was extended
to the United kingdom. The basis of the estimation is the estate
multiplier method. The method and coverage are being continually
improved and only recently the Inland Revenue has published new
and consistent estimates for the UK as far back as 1976 (Good,
1990; Stewart, 1991).
The estate or mortality multipliers used by
the Inland Revenue for Northern Ireland are the same as those
for England and Wales. The do not, however, publish the estimates
with a regional or country break-down. The mortality multipliers
are published and could be applied to Northern Ireland estates
from Inheritance Tax data. The problem here is that since 1974
when the Inland Revenue took over the Estate Duty Office for Northern
Ireland from the Northern Ireland Department of Finance, there
have been no separately published data on the estates of deceased
persons for the Province. The upshot is that even private academic
studies relate at latest to 1965-66 (Corley, 1962; Lyons, 1972).
The Survey of Personal Incomes (SPI)
The Inland Revenue annually samples, and has
done so since 1962-3, over 60,000 tax cases.
The sampling fractions vary from 1 in 3 for higher incomes to
1 in 2,000 for average income employees. In years before 1962-3
there were a series of surveys at five yearly intervals, often
with samples of over 1 million cases (Stark, 1978). The sample
until 1988-89 was undertaken by Tax Offices from their tax return
records. Computerized databases are now used. The results which
are now published in the annual Inland Revenue Statistics are
presented after "grossing up".
The main problem with the SPI is that the
coverage of investment income is incomplete, though the Inland
Revenue since 1985/86 has endeavoured to allocate "missing"
investment income. There are also problems with respect to part
year incomes, some of which spuriously inflate
low incomes - e.g. those of persons dying during the year and
others which may be counted twice, such as those of women marrying
during the year.
The Surveys are restricted to incomes subject
to tax. The income recipient is the tax unit - that is single
persons or married couples. Income units below the tax threshold
are excluded as are certain types of non-taxable incomes - eg
child benefits. At the national level distributions are available
detailing income type, marital status, wives' income, deductions
and so on. In the days when tax allowances could be claimed for
children, family size information was also available.
Country distributions - Northern Ireland,
Scotland, England and Wales - have always been available in every
post-war survey. In the early quinquennial survey these provided
similar detail to the national data. However, since 1962-3
with the smaller annual surveys, country data is restricted to
analysis of total income and sub-divisions by three classes of
earned income - profits and professional earnings; employment
income and pensions. Data on investment income and deductions
is not given at this level of dissaggregation. The Northern Ireland
figures are presented in slightly more detailed form in the Northern
Ireland Abstract of Statistics. There are also similar published
data for all regions and summary data for countries, including
Northern Ireland. In 1987/88 we estimate that the SPI accounted
for 60% of total personal income in Northern Ireland or 73% of
total personal factor income (excluding imputed rent).
The Inland Revenue inform us that they have
from time to time supplied more detailed regional information,
subject to confidentiality and statistical significance, to bona
fide academic researchers. The anonymised data tapes from the
SPI for 1985/86 are lodged with the ESRC Data Archive (SN 2561).
It is planned to lodge later years. However, it is not possible
to extract regional or Northern Irish data from the Data Archive
The Northern Ireland New Earnings Survey
The history, conduct and structure of the
Northern Ireland New Earnings Survey (NINES) is identical to that
of Great Britain. It began in 1968 and since 1975 has been a 1%
sample of all employees on a PAYE scheme. In fact all those with
National Insurance Card numbers ending in a specific pair of digits
(-14-) are sampled. The employers of such card
holders are asked by the Inland Revenue - backed by statutory
authority - to complete a questionnaire regarding pay before tax
and National Insurance, bonuses, overtime, hours worked plus age,
sex, occupation and industrial classification. All information
refers to a specific week in April of each year (usually the second).
The response rate by employees is over 90%,
such that accurate "grossing up" factors can be calculated
from which it can be concluded that the "coverage" of
full-time employees on adult rates whose earnings are above the
deduction card limits for income tax and National Insurance is
virtually complete. Though some returns relate to part-time employees
and some even to those below the above thresholds, these are not
considered reliable and are invariably omitted from the published
survey results. The only other possible deficiency with the survey
is that it is technically possible to double count persons who
are on more than one PAYE scheme. The same National Insurance
Card digit identification is adopted each year. This means that
a substantial proportion of the sample is matched with the previous
year (73% in the 1991 NIHES). This increases substantially the
reliability of the estimates of year to year changes in earnings.
The Inland Revenue pass on the main Great
Britain results to the Department of Employment who annually publish
the New Earnings Survey - six volumes of considerably detailed
statistics, one of which includes dissaggregation by the standard
regions - metropolitan and country areas of Great Britain. Northern
Ireland is excluded from all materjal in the GB NES. The GB NES
database is lodged he ESRC Data Archive.
The results of the survey undertaken
by the Inland Revenue
for Northern Ireland are passed on as "hard copy" to
the Northern Ireland Department of Economic Develop-who publish
a separate NINES. The NINES usually appears
six months after the first GB volume. It comprises slightly over
4,000 persons sample compared to over 15,000 for GB. Consequently
the feasible degree of disaggregation
for the NINES is a lot less than for GB.
Average weekly earnings data
for full-time employees on rates is published separately by sex;
manual/non-manual; all one digit with some two digit Standard
Occupational Classification (SOC); all one digit major SIC classification
and for those who are in Belfast travel to work area and
the rest of the Province. Standard error estimates are also given
in many instances.
Median and quartile published data are restricted
to sex; manual/non-manual dissaggregation with the definitions
varying from including and excluding overtime and
those who pay was not affected by absence.
A detailed distributon by 23 earnings ranges is, however, presented
for males, females, boys and girls, both full-time and part-time
) and for all the sample as well as only for those whose pay was
not affected by absence.
The Department of Economic Development (DED)
will supply more detailed break-down on request
to bona fide researchers and subject to constraints on statistical
significance. The matched sample results are
available also this way as are a greater break-down by occupation
and industry. The DED will also supply "grossing-up"
factors on request.
The NIHES is not deposited with ESRC Data
Archive. However, a detailed study using the NINES for the years
to 1983 by R. D. Harris is lodged with the Archive (2211)
Good, J. F. (1990) "Estimates
of the Distribution of Personal Wealth", Economic
Trends, October.Return to Contents
Stewart, J. (1991) "Estimate of the Distribution
of Personal Wealth II: Marketable Wealth and
Pension Rights of Individuals, 1976-1989",
Economic Trends, November.
Corley, T. A. B. (1962) "The Personal Wealth
of Northern Ireland 1920-1960", Journal
of the Statistical and Social Inquiry Society of Ireland.
Lyons, P. M. (1972) "The Distribution of Personal Wealth
in Northern Ireland", Economic and Social Review.
Stark, T. (1978) "Personal Incomes" in Volume VI
SSRC/RSS Reviews of United Kingdom
Statistical Sources , Pergamon Press.