International Wealth Index (IWI)

Asset based wealth indices are widely used instruments for measuring the economic situation of households in developing countries. Many household surveys for these countries include such an index based on the possession of consumer durables and housing characteristics.

Wealth indices owe this success to their intuitive appeal, wide availability, ease of computation, and reliability of measurement. However, in spite of these desirable properties, they suffer of one great problem: They are not comparable between surveys.

For each survey a new wealth index is constructed which is not related to indices used in other surveys. Studying wealth differences among countries or wealth changes over time is therefore not possible.

To solve this problem, a more general wealth index is needed that measures the economic situation of households always in a similar way.

The International Wealth Index (IWI) developed by Smits & Steendijk (2015) is such a general index. IWI runs from 0 to 100, with 0 representing households having none of the assets and lowest quality housing and 100 representing households having all assets and highest quality housing.

IWI is designed to be as general and flexible as possible. It can easily be added to existing and new surveys by including information on a basic set of assets into a simple additive formula.

Detailed information on IWI can be found at the International Wealth Index pages of the the Global Data Lab. There you can also find help files for adding IWI to your data and download the value of IWI for over 1400 subnational regions in 130+ low and middle income countries.

Background paper

Detailed information about IWI can be found in:
Smits, Jeroen & Roel Steendijk (2015). The international wealth index (IWI). Social Indicators Research, 122(1), 65-85. Download paper here.

Papers using IWI (selection)

Bras, H & J. Smits (2021). Contexts of Reproduction. Gender Dynamics and Unintended Pregnancy in sub-Saharan Africa. Journal of Marriage and Family, 84(2), 438-456.

Monden, C. & J. Smits (2017). Mortality among twins and singletons in sub-Saharan Africa between 1995 and 2014. Lancet Global Health, 5(7), e673–e679.

Gershman, Boris & Diego Rivera (2018). Subnational diversity in Sub-Saharan Africa: Insights from a new dataset. Journal of Development Economics, 133, 231-263.

Smits, J & I. Permanyer (2019). The Subnational Human Development Database. (Nature) Scientific Data, 6, 190038.

Berendsen, M., J. Smits, M. Netea & A. Van der Ven (2016). Non-specific effects of vaccines and stunting: Timing may be essential. Ebiomedicine, 8, 341-348.

Pesando, L. M. (2021). Educational assortative mating in sub-Saharan Africa: Compositional changes and implica tions for house hold wealth inequality. Demography, 58, 571–602.

De Jong, E., J. Smits, & A. Longwe (2017). Estimating the causal effect of fertility on women's employment in Africa using twins. World Development, 90, 360-368.

Berendsen, M., B. van Gijzel, J. Smits, Q. De Mast, P. Aaby, C. Benn, M. Netea, A. Van der Ven (2019). BCG vaccination is associated with reduced malaria prevalence in children under the age of five in sub-Saharan Africa. BMJ Global Health, 4, e00186.

Belmin, C., Hoffmann, R., Elkasabi, M. et al. LivWell (2022).:A sub-national Dataset on the Living Conditions of Women and their Well-being for 52 Countries. (Nature) Scientific Data 9, 719. https://doi.org/10.1038/s41597-022-01824-2

Crombach, L & J. Smits (submitted). Understanding the Urban-Rural Fertility Divide in sub-Saharan Africa: The Critical Role of Social Isolation.

Smits, J & I. Permanyer (2019). The Subnational Human Development Database. (Nature) Scientific Data, 6, 190038.

Mank, I., Vandormael, A., Traoré, I. et al. Dietary habits associated with growth development of children aged < 5 years in the Nouna Health and Demographic Surveillance System, Burkina Faso. Nutr J 19, 81 (2020). https://doi.org/10.1186/s12937-020-00591-3

Ebbers, A. & J. Smits (2022). Household and context-level determinants of birth registration in sub-Saharan Africa. PLoS ONE, 174, e0265882.

Lee, Kamwoo & Jeanine Braithwaite (2022). High-resolution poverty maps in Sub-Saharan Africa. World Development, 159, November 2022, 106028.

Wibaek, Rasmus e.a. (2019). Body mass index trajectories in early childhood in relation to cardiometabolic risk profile and body composition at 5 years of age. The American Journal of Clinical Nutrition, 110(5), 1175-1185.

Alcorta, L., J. Smits & H. Swedlund (2020). Discrimination and ethnic conflict: a dyadic analysis of politically-excluded groups in sub-Saharan Africa. International Interactions.46(2), 251–273.

Alcorta, L., J. Smits & H. Swetlund (2018). Inequality and ethnic conflict in Sub-Saharan Africa. Social Forces, 97(2), 769–792.

Alcorta, L., J. Smits, H. Swedlund & E. De Jong (2020). The ‘Dark Side’ of Social Capital: A Cross-National Examination of the Relationship Between Social Capital and Violence in Africa. Social Indicators Research,149, 445–465.

Schrijner, S. & J. Smits. (2018). Grandparents and Children's Stunting in sub-Saharan Africa. Social Science and Medicine, 205, 90-98.

Schrijner, S. & J. Smits (2018). Grandmothers and Children’s Schooling in Sub-Saharan Africa. Human Nature, 29(1), 65–89.

Schrijner, S. & J. Smits (2019). Paternity Uncertainty or Male Dominance? Paternal versus Maternal Grandmothers' Contribution to Children's Schooling in Sub-Saharan Africa. Journal of Child and Family Studies.

Permanyer, I. & J. Smits. (2020). Inequality in human development across the globe. Population and Development Review. 46(3), 583-601.

Deurzen I van, van Oorschot W, van Ingen E (2014) The Link between Inequality and Population Health in Low and Middle Income Countries: Policy Myth or Social Reality? PLoS ONE 9(12): e115109. https://doi.org/10.1371/journal.pone.0115109

Bauza, V.; Guest, J. S. The Effect of Young Children’s Faeces Disposal Practices on Child Growth: Evidence from 34 Countries. Trop. Med. Int. Health 2017, 22 (10), 1233– 1248, DOI: 10.1111/tmi.12930

Woolard, K., S. Munira, K. Jesmin & D. Hruschka (2021). Evaluating the performance of five asset-based wealth indices in predicting socioeconomic position in rural Bangladesh. Field Methods, 34(2). https://doi.org/10.1177/1525822X211020650.

Mayfour, K.W. & D. Hruschka Assessing comparative asset-based measures of material wealth as predictors of physical growth and mortality. SSM-Population Health, 17 (2022), Article 101065.

Wildeman, J., J. Smits & S. Schrijner (2023). Ethnic variation in fertility preferences in sub-Saharan Africa. Population Research and Policy Review, 42.