The Basic Necessities Survey (BNS) is a participatory and rights-oriented approach to the measurement of poverty. It has been most widely used by non-government organisations working with local communities on nature conservation issues in developing economies.The Conservation Social Science Partnership > Resources > Basic Necessities Survey (BNS). (2021). The Conservation Social Science Partnership. https://impactconsosci.azurewebsites.net/Resources/Form-Library/Form?FormID=1Woodhouse, E., Homewood, K. M., Beauchamp, E., Clements, T., McCabe, J. T., Wilkie, D., & Milner-Gulland, E. J. (2017). Understanding Human Well-being for Conservation: A Locally Driven, Mixed Methods Approach. In E. J. Milner-Gulland, E. Nicholson, & N. Bunnefeld (Eds.), Decision-Making in Conservation and Natural Resource Management: Models for Interdisciplinary Approaches (pp. 97–122). Cambridge University Press. https://doi.org/10.1017/9781316135938.005Schrekenberg, K. (2010). Social Assessment of Conservation Initiatives: A Review of Rapid Methodologies. IIED. It is a specific type of multidimensional measure of poverty,Afonso, H., LaFleur, M., & Alarcón, D. (2015). Multidimensional Poverty. UN/DESA. https://www.un.org/en/development/desa/policy/wess/wess_dev_issues/dsp_policy_03.pdf with its origins in research on "consensual" definitions of poverty.
Definition and construction
As first described in 1998: A focus group is used to generate a menu of items and activities that people may think are "basic necessities". Such a list should include items whose likely status as necessities is unclear, as well as those seen as more likely to be seen as necessities
A representative sample of households in a community is then surveyed, asking two types of questions:
1. "Which of the items on this list do you think are basic necessities which everyone should have and which no one should have to do without?"
2. "Which of these items does your household have now?"
For each item, the percentage of respondents who believe the item to be a basic necessity is calculated. Only items which more than 50% of respondents consider to be basic necessities are recognised as such. The percentage of respondents who consider each item to be a "basic necessity" is then treated as the weighting for that item. A poverty score is then calculated for each respondent by adding together the weighting for all the basic necessity items which the respondent actually possesses, divided by the total of the weightings for all the "basic necessity" items (i.e., the total possible score). If the respondent has all the `basic necessities', their score will be 100%, if they have none of the `basic necessities', their score will be 0%.
Origins
The 1998 design of the BNS built on earlier work on the "consensual definition of poverty" by Mack and Lansley in the UKMack, J., Lansley, Stewart. (1985). Poor Britain. G. Allen & Unwin. https://www.poverty.ac.uk/free-resources/poor-britain and Hallerod in Sweden.Hallerod, B. (1994). A new approach to the direct consensual measurement of poverty. SPRC Discussion Paper No. 50. https://library.bsl.org.au/jspui/bitstream/1/209/1/A%20New%20Approach%20to%20the%20direct.pdf Mack and Lansley defined items as necessities if, as above, more than 50% of respondents identified them as such, Results were summarised in terms of percentages of the respondents lacking 1, 2, 3 to N number of necessities. They defined poverty as the lack of three or more such items, after identifying this cut-off point by using ".. a range of sequential statistical procedures...". In contrast, Hallerod rejected the 50% cut off because it was literally not a measure of consensus. And more contestably, Hallerod argued that 50% was an "arbitrary" cut-off point. His alternative approach, called the "Proportional Deprivation Index" generated a score which was the sum of the weightings of all the items a respondent possessed, treated as a percentage of the maximum possible score (the sum of all weightings). These calculations included weightings of less than 50%.
The design of the BNS combined the aggregation of weightings used by Hallerod, but only applied this to items rated as necessities by more than 50% of respondents, the distinction used by Mack and Lansley. The 50% cut-off was described and justified as a democratic (but not consensual) because of its widespread use in electoral systems. The BNS is described as rights-oriented, because of how necessities are defined, being items and activities "which everyone should have and which no one should have to do without". There are no additional questions about whether a reported lack is chosen or not, as was the case the Mack and Lansley study.
Use
The BNS was first used in 1997 by ActionAid in Vietnam, as part of a baseline survey of poverty of households in four communes of Can Loc district of Ha Tinh province, at the beginning of the Ha Tinh Integrated Poverty Alleviation Programme (HTPAP).McGillivray, M., David Carpenter, Phung Duc Tung, Quynh, C. T. T., & Aure, E. (2015). Historical Overview: Development Co-Operation Between the United Kingdom and Vietnam. Landell Mils Development Consultants. https://iati.fcdo.gov.uk/iati_documents/5263424.odt The same survey design was repeated in 2006, two years after the end of the programme . Changes in the distribution of poverty (BNS) scores between 1997 and 2006 can be seen in the first scatterplot (Figure 1).
In 2007 the BNS methodology was publicised in two joint USAID / Wildlife Conservation Societypublications, on the use of householdWilkie, D. (2007). Household surveys—A tool for conservation design, action and monitoring. USAID Wildlife Conservation Society Technical Manual 4. http://s3.amazonaws.com/WCSResources/file_20110518_073650_Manual_HouseholdSurveys_CxUCh.pdf and livelihood surveys.USAID/WCS. (2007). Livelihood Surveys: A tool for conservation design, action and monitoring. USAID TransLink https://rmportal.net/library/content/translinks/translinks-2007/wildlife-conservation-society/LivelihoodSurveys_Manual_WCS_2007.pdf/view Since then, the BNS has been used in Uganda,Harrison, M. (2013). Penetrating the Impenetrable: Establishing profiles and motivations of resource users at Bwindi Impenetrable National Park, Uganda. 100.Travers, H., Mwedde, G., Archer, L., Roe, D., Plumptre, A., Baker, J., Rwetsiba, A., & Milner-Gulland, E. J. (2017). Taking action against wildlife crime in Uganda. 77. Brazil,McFarland, B. J. (2018). Payments for Ecosystem Services. In B. J. McFarland (Ed.), Conservation of Tropical Rainforests: A Review of Financial and Strategic Solutions (pp. 337–429). Springer International Publishing. https://doi.org/10.1007/978-3-319-63236-0_11 Cambodia,Wildlife Conservation Society, Clements, T., Neang, M., Royal University of Agriculture, Milner-Gulland, E., University of Oxford, Travers, H., & Cambridge Conservation Solutions. (2020). Measuring impacts of conservation interventions on human well-being and the environment in Northern Cambodia (2020th ed.). International Initiative for Impact Evaluation (3ie). https://doi.org/10.23846/DPW1IE106 China,Duan, W., & Wen, Y. (2017). Impacts of protected areas on local livelihoods: Evidence of giant panda biosphere reserves in Sichuan Province, China. Land Use Policy, 68, 168–178. https://doi.org/10.1016/j.landusepol.2017.07.015 Democratic Republic of Congo,Spira, C., Kirkby, A. E., & Plumptre, A. J. (2019). Understanding ranger motivation and job satisfaction to improve wildlife protection in Kahuzi–Biega National Park, eastern Democratic Republic of the Congo. Oryx, 1–9. https://doi.org/10.1017/S0030605318000856 Kenya,Mutune, J. M., Wahome, R. G., & Mungai, D. N. (2015). Local Participation in Community Forest Associations: A Case Study of Sururu and Eburu Forests, Kenya. http://erepository.uonbi.ac.ke/handle/11295/96088 Nigeria,Detoeuf, D., Wieland, M., & Wilkie, D. (2020). Guide 2.0 to the Modified Basic Necessities Survey: Why and How to Conduct Digital-Based BNS in Conservation Landscapes. Page 4. https://doi.org/10.19121/2020.Report.38385 Madagascar,Savage, J. (2020). A Report for PROJECT ORATSIMBA A Baseline Socioeconomic Assessment of Lobster Fishing Communities in Southeast Madagascar. Seed Madagascar. https://madagascar.co.uk/application/files/7515/8684/3984/Baseline_Socioeconomic_Assessment.pdf Malawivan Velden, J. L., Wilson, K., Lindsey, P. A., McCallum, H., Moyo, B. H. Z., & Biggs, D. (2020). Bushmeat hunting and consumption is a pervasive issue in African savannahs: Insights from four protected areas in Malawi. Biodiversity and Conservation, 29(4), 1443–1464. https://doi.org/10.1007/s10531-020-01944-4 MaliNteziyaremye, A., & MkNelly, B. (2001). Mali Poverty Outreach Study of the Kafo Jiginew and Nyèsigiso Credit and Savings with Education Programs. 5. and Rwanda. This diffusion was aided by USAID's publication in 2015 of "A Guide To The Modified Basic Necessities Survey: Why And How To Conduct BNS In Conservation Landscapes",Wilkie, D., Wieland, M., & Detoeuf, D. (2015). A Guide to the Modified Basic Necessities Survey Why and How to Conduct BNS in Conservation Landscapes. USAID.https://global.wcs.org/Resources/Publications/Publications-Search-II/ctl/view/mid/13340/pubid/DMX2864300000.aspx based on WCS and others experiences in these countries . The purpose was "to bring to conservation practitioners a low-cost tool for credibly assessing how conservation actions affect families' livelihoods and sense of well-being and tracking changes within and across villages over time" . An updated version of the Guide was subsequently published in 2020.Detoeuf, D., Wieland, M., & Wilkie, D. (2020). Guide 2.0 to the Modified Basic Necessities Survey: Why and How to Conduct Digital-Based BNS in Conservation Landscapes. https://doi.org/10.19121/2020.Report.38385
An updated bibliography of publications about the use the BNS, and some related methods, is maintained online.Zotero Groups - Basic Necessities Survey. https://www.zotero.org/groups/2440491/basic_necessities_survey/items/Y2ZTP9J4/library
Adaptations
The 2015 WCSWilkie, D., Wieland, M., & Detoeuf, D. (2015). A Guide to the Modified Basic Necessities Survey Why and How to Conduct Bns in Conservation Landscapes. USAID. https://global.wcs.org/Resources/Publications/Publications-Search-II/ctl/view/mid/13340/pubid/DMX2864300000.aspx modification of the BNS included additional questions aimed at quantifying the assets identified as basic necessities and possessed by respondents, then the calculation of a household wealth index based on that data and local price information. The "Wealth Index" made it possible to differentiate amongst the non-poor families, i.e., those that scored 100% on the BNS. The BNS scoring process, described above, was retained in its original form.
The 2006 survey in Vietnam included an additional question: "Compared to other households in this commune, do you think your household is poor, or not poor?" Overall, there was a 0.95 inverse correlation between the BNS score and the proportion of respondents who said they were poor. In other words, most poorer households reported themselves as poor and most less poor households reported themselves as not poor. In total, 35% reported themselves as "poor". Assuming that errors in self-reporting are equal in both directions (non-poor reporting as poor, poor reporting as non-poor) this aggregated response provided a "head count" measure of poverty, which complemented the "depth of poverty" description of the BNS score distribution. It also provided a means of identifying an observable cut-off point in the range of BNS score, which defines a poverty line: 35% of respondents were found below the BNS score of 75%, which now defines the poverty line in BNS score terms. Other assumptions about the distribution of self-reporting errors generate other cut-off points.
Comparisons with other methods