Changing how poverty is measured and understood
Submitting InstitutionUniversity of Essex
Unit of AssessmentEconomics and Econometrics
Summary Impact TypePolitical
Research Subject Area(s)
Economics: Applied Economics, Econometrics
Summary of the impact
Essex research, conducted between 1994 and 2010, has provided a new way
for the UK Government to measure income poverty, leading to a measure of
persistent poverty being included in the Child Poverty Act 2010.
The research has enriched policymakers' understanding of changes in
inequality and provided a framework for the analysis of poverty dynamics.
It has also changed the way in which the Joseph Rowntree Foundation
approaches its research and policy work on poverty. A sub-strand of work,
on how incomes change after couples separate, has informed policy
development work by the charity Gingerbread.
Shortly after longitudinal micro-data on UK household income first became
available, Stephen Jenkins and colleagues at Essex, in a programme of work
from 1994 to 2010, developed techniques to study changes to income
inequality and income-based measures of poverty. They produced new
substantive results on the extent and nature of dynamics in household
income and poverty in the UK.
In the mid-1990s, using the newly-available data on household income,
Jenkins and Jarvis (1998) gave the first robust impression of the extent
of income mobility in the UK, showing that much of this involves small
changes in household income. As more data became available, Jenkins and
Rigg (2001) were able to go beyond the usual conventional way of analysing
low income in the UK (which was to measure incomes at a point in time, and
estimate what fraction lives in a household whose equivalised income is
below 60% of the contemporaneous national median) to both construct
measures of persistent poverty, and analyse the dynamics in the usual
poverty measure (showing, for example, that one in three individuals
experience relative poverty at least once in a four-year period).
Cappellari and Jenkins (2002) and Jenkins and Rigg (2001), the latter
commissioned directly by the Department for Work and Pensions, found that
children, pensioners, female adults, lone parent families, and working-age
workless families were all subgroups that are especially likely to
experience persistent and recurrent poverty. These findings allow policy
initiatives to be directed towards the most vulnerable. Jenkins and Rigg
(2001) analysed the factors associated with moves in and out of poverty,
finding that changes in a household's labour earnings accounted for 62% of
exits from poverty and 44% of entries to poverty — this is one of the key
pieces of evidence behind many UK policymakers' claims that work is the
best route out of poverty.
Related work (Jenkins, 2008) using the same longitudinal data on
household incomes has documented the changes in income that are associated
with the breakdown of marital partnerships, and established the
substantial average decline in equivalised income experienced by
separating women, whereas separating men see an average rise in
The research has involved significant methodological developments.
Cappellari and Jenkins (2004) modelled poverty transitions that account
for state dependence, initial poverty status and non-random attrition.
Jenkins (2009) developed, in work commissioned by the National Equality
Panel, a modelling framework for describing income-age trajectories that
summarises not only the average profile for a group of similar
individuals, but also how individual trajectories differ from the group
average. Jenkins and Van Kerm (2006) show how, for any member of the
generalised Gini class of indices, the change in inequality between two
points in time can be additively decomposed into two components, one
summarising mobility in the form of re-ranking, and one summarising
progressivity in income growth (i.e. whether income growth is pro-poor
rather than pro-rich). This allows for a more meaningful assessment of the
extent of income mobility in society.
The research team included:
Stephen Jenkins, Professor, at Essex 1994 - 2010
Lorenzo Cappellari, Nuffield Career Development Fellow, at Essex 2000 - 2001
Francesco Devicienti, Research Officer, at Essex 1999 - 2001
Sarah Jarvis, Senior Research Officer, at Essex 1995 - 1999
John Rigg, Senior Research Officer, at Essex 1999 - 2002
References to the research
Jenkins, S. P. and S. Jarvis (1998) How much income mobility is there in
Britain? Economic Journal, 108 (447): 428-443. DOI:
Jenkins, S. P. and J. A. Rigg, with F. Devicienti (2001) The dynamics
of poverty in Britain. DWP Research Report 157. ISBN 1841234176
Cappellari, L. and S. P. Jenkins (2002) Who stays poor? Who becomes poor?
Economic Journal 112 (478): C60-C67. DOI: 10.1111/1468-0297.00028
Cappellari, L. and S. P. Jenkins (2004) Modelling low income transitions.
Journal of Applied Econometrics, 19 (5): 593-610. DOI:
Jenkins, S. P. and P. Van Kerm (2006) Trends in income inequality,
pro-poor income growth and income mobility. Oxford Economic Papers
58 (3): 531-548. DOI: 10.1093/oep/gpl014
Jenkins, S. P. (2009) Spaghetti Unravelled: a model-based description of
differences in income-age trajectories. ISER Working Paper, 2009-30,
University of Essex, Colchester, UK.
(Later published as chapter 7 of Jenkins, S.P., 2011, Changing
fortunes: income mobility and poverty dynamics in Britain, Oxford:
OUP. ISBN 0199226431)
The research was supported by the following grants (total £3,552,538):
Jenkins, S. P. Earnings and income mobility in Britain. The
Nuffield Foundation, 01.10.00 to 30.09.03, £88,972.
Jenkins, S. P. and M. Francesconi, BHPS Analysis: the dynamics of
poverty. Department of Social Security, 01.12.00 to 31.08.01,
Taylor, M., R. Berthoud and S. P. Jenkins, Tracking the circumstances
of those with the lowest incomes. Social Exclusion Unit, 04.09.03 to
Gershuny, J. ESRC Research Centre on Micro-Social Change. ESRC,
01.10.04 to 30.09.09, £3,331,616.
Jenkins, S. P. National Equality Panel. Government Equality
Office, 07.03.09 to 31.05.09, £10,000.
Details of the impact
The research has contributed significantly to the UK policy debate, and
the policy response, surrounding poverty and income inequality. It has
done this partly by providing new empirical evidence about the nature of
poverty and inequality in the UK, which has formed the basis of useful
inputs for policymakers, and partly by showing the value of a longitudinal
analysis of income inequality and poverty in the UK. The research has had
impact on government policy and on third- sector organisations.
Impact on government legislation and policy
The main impact of this research has been to fundamentally change the way
in which poverty statistics are reported in Britain. Prior to this
research, the annual official poverty statistics, as reported in the
Department for Work and Pensions' report, Households Below Average Income
(HBAI), concentrated solely on point-in-time measures of poverty and
income inequality. Because of Essex research on poverty and low-income
dynamics, the HBAI series now routinely produce statistics relating to
income-dynamics poverty persistence and poverty transitions. The most
recent example of this is the DWP's 2011 Low-Income Dynamics
report. Section 4 of this report is on `Transitions into and out of Low
Income' and explicitly states that the methodology used is that developed
by Jenkins and Rigg (2001) [corroborating source 1].
As a direct consequence of the change to the HBAI reports, a measure of
persistent poverty now forms one of the four statutory measures of child
poverty named in the Child Poverty Act 2010, against which future
governments have to report progress [corroborating source 2]. Before
bringing forward the Bill, the previous government consulted on how they
should define and measure child poverty, and the consultation document 
refers to research by Jenkins and Rigg (2001). These sorts of statistics
continue to inform policymaking at the highest level: Figure 1.3 of the
Cabinet Office's 2010 State of the nation report—a document which
represents the current government's overall approach to poverty and
disadvantage—cites statistics on persistent poverty . This impact was
generated largely through the academic outputs in Section 3, but also
through writing reports for government departments and publishing more
accessible versions of academic findings.
Essex research informed the work of the National Equality Panel (NEP),
which was established by the Labour government in 2008 to identify the
extent and depth of inequality in Britain. The NEP's final report, An
anatomy of economic inequality in the UK, identified a range of
deep-seated and systematic differences between social groups across many
dimensions of life, and it has attracted a great deal of policy and media
attention (over 400 items of media coverage since January 2010). Stephen
Jenkins was a member of the NEP, and his work directly influenced the
panel's thinking through Jenkins (2009), which was commissioned to support
the panel's deliberations. The final report makes extensive reference to
Jenkins' research .
Impact on the third sector
The research has also had significant impact on the way in which
charitable organisations understand poverty. Essex research has been used
extensively by The Joseph Rowntree Foundation (JRF), which has stated:
"The way that JRF approaches poverty (as outlined for example in its
strategic plan and new programme to develop anti-poverty strategies) is
informed by research undertaken by Stephen Jenkins while he was at the
University of Essex Institute for Social and Economic Research... A clear
thread of Stephen's work can be seen within JRF thinking on poverty over
the last decade, influencing two major reviews and at least five separate
programmes of research" .
The JRF's programme on `recurrent poverty' was informed by Essex
research, which is demonstrated by the very concept being drawn from
Jenkins' work  and the final summary report in 2010  directly
referencing Jenkins and Rigg (2001). This review then fed into a further
JRF programme on the future of the UK labour market, which again draws
heavily on the dynamic approach to poverty developed at Essex .
Furthermore, the JRF's strategic plan states that one of its aims is to
"equip policy-makers around the UK to understand the complex causes and
dynamics of poverty, including how it relates to ethnicity, disability and
ill-health across the age range"  . A JRF programme called
`Anti-poverty strategies for the UK', which began in 2012, reflects these
strategic aims and has as its core principle the ideas that poverty is
dynamic and should be understood over the life-course .
Jenkins' work on income-changes after divorce has provided evidence on
the link between single parenthood and poverty, which has been central to
policy development work by the charity Gingerbread, which represents lone
"Gingerbread has made significant use of research work undertaken by
Stephen Jenkins on income changes after couples separate. This has been
particularly valuable for us in policy development relating to the
incidence and experience of poverty in single parent families. This, in
turn, has played a particularly key role in our influencing work on child
poverty, as a significant component in explaining why children in single
parent families are disproportionately likely to be affected by poverty,
and informing our development of relevant policy measures to tackle
Essex research is referred to frequently in Gingerbread's policy
documents, including briefing materials and responses to government
consultations. For instance, Jenkins (2008) is cited in the charity's Single
parents, equal families (2009) report  and Gingerbread has
stated that Essex research has informed a further four policy documents,
including its submission to the Independent (Frank Field) review of
poverty and life chances and its response to government consultation
on Measuring child poverty: A consultation on better measures of child
Sources to corroborate the impact
All documents are available from HEI on request.
 Department for Work and Pensions (2011) Low-Income Dynamics
1991-2008 (Great Britain). London: DWP. See pp. 21-22.
 HM Government (2010) Child Poverty Act 2010. London:
Stationery Office. See Parts 6 & 7.
 Child Poverty Unit (2009) Ending child poverty: Making it happen,
HM Government. See p. 22 and footnotes 37 & 39. http://www.education.gov.uk/consultations/downloadableDocs/8061-CPU-Ending%20Child%20Poverty.pdf
 Cabinet Office (2010) State of the nation. See Figure 1.3.
 Hills, J., M. Brewer, S. Jenkins, R. Lister, R. Lupton, S. Machin, C.
Mills, T. Modood, T. Rees and S. Riddell (2010) An anatomy of economic
inequality in the UK: Report of the National Equality Panel,
Government Equalities Office, London. See footnotes 41, 46, 180, 232 and
section 11.5. Available as CASEReport 60: http://eprints.lse.ac.uk/28344/1/CASEreport60.pdf
 Head of Poverty, Policy and Research, Joseph Rowntree Foundation.
 Goulden, C. (2010) Cycles of unemployment and low pay. See p.
 Joseph Rowntree Foundation, Strategic plan 2012-2014. See p.
 Director of Policy, Advice and Communications, Gingerbread.
 Gingerbread (2009) Single parents, equal families, London:
Gingerbread. See Footnote 40 of item 8. http://www.gingerbread.org.uk/uploads/media/17/6841.pdf