Household income data collected during fieldwork in November
2014produced the mean and median household incomes153shown 153
Incomes are known to be signifi- cantly positively skewed, and this is no exception for the income data we collected for the city of Nampula and towns of Ribáuè and Liúpo. For such data, medians or geometric means (i.e.back-transformed means of log- transformed income) provide a much more accurate representation of the centre of the distribution, but neither of these are reported in the IOF.
in Table22. Mean monthly incomes are significantly higher than those reported for Nampula Province in the2008-2009IOF with the mean income for the city of Nampula being nearly twice that of the total reported for urban Mozambique as a whole. While at first glance this may seem unusually high, we note that this would be consistent with the doubling of mean incomes observed over the last two waves of the IOF and could reflect the increased economic activity along the Nacala Corridor. Additionally, as the largest city in the province, it would not be unexpected that mean house- hold income for the city of Nampula would in fact be significantly higher than other urban centres within the province154
. Incomes for
154
We additionally note that the water and sanitation situation observed in the areas sampled far exceeded that reported for Nampula as a whole in the2011DHS PLUS, suggesting that either there has been a significant increase in household income or our sample included a greater proportion of households with higher SES than what was observed in the DHS in2011. the towns of Ribáuè and Liúpo would be consistent with less rapid
economic growth than what was experienced in the city of Nam- pula, placing them at roughly the anticipated provincial average.
Town/City Mean income Median income
Nampula 10,767.92(9,202.30,12,333.54) MZN 3,041.67MZN Ribáuè 3,894.47(3,231.64,4,557.31) MZN 2,500MZN Liúpo 3,088.34(2,428.65,3,748.03) MZN 1,510.42MZN
Table22: Mean monthly household incomes (with accompanying95% confidence intervals) and median monthly household incomes for the city of Nampula and towns of Ribáuè and Liúpo, as reported in November 2014.
Publicly available survey data for household incomes for the city of Nampula and town of Liúpo do not appear to exist for previous household surveys carried out in these locations, although income data were collected for the town of Ribáuè in June2012in a short WTP survey carried out by UNICEF Mozambique and AIAS as part of NAMWASH [UNICEF and Administração de Infra-estruturas de Água e Saneamento,2012]155. This survey was carried out to
155
UNICEF and Administração de Infra-estruturas de Água e Sanea- mento. Willingness to Pay for an Improved Water Service: Ribáuè Munici- pality, Ribáuè District, Nampula Province, Mozambique. UNICEF and Adminis- tração de Infra-estruturas de Água e Saneamento, Maputo,2012
understand preferences and WTP for various forms of delivery of improved water156
as well as capacity to pay and current expendi-
156
This survey focused on delivery of water to households through piped in- frastructure in the forms of household connections, yard taps, and standpipes.
ture for water. In this survey of371households, estimated mean household income was reported to be below750MZN per month
f ac t o r s i n f l u e n c i n g i n c o m e a n d t h e w i l l i n g n e s s t o r e v e a l i t 71
for seventeen of nineteen neighbourhoods157
with the remaining 157
The overwhelming majority of these neighbourhoods were reported to have a mean household income in the range of200-300MZN per month.
two neighbourhoods having mean household incomes of roughly 1,500MZN and3,000MZN per month. These totals suggest a much worse economic situation than totals obtained from our survey in November2014.
There are a number of possible reasons for these disparities. A simple explanation would be significant changes in household earn- ing over the two year period from2012to2014due to economic activity in the region158
. Another reason could be the stated pur- 158
As part of the Nacala Corridor de- velopment, there have been significant rail and road projects in close proxim- ity to Ribáuè. UNICEF Mozambique reported costs for delivery of water infrastructure to Ribáuè increasing sig- nificantly due to competing economic opportunities in the area with total expenditure being approximately33% higher than anticipated.
pose of the WTP survey as presented to respondents, which made it clear that the survey was trying to measure both capacity and WTP for improved water that would be provided as part of NAMWASH. Households may have believed that it would be beneficial to under- state income as well as their WTP in the hope of more favourable water tariffs for the infrastructure that was to be provided. The location of the question in the survey could also partly be respon- sible, as questions about income occurred at the very start of the WTP survey before enumerators could establish a rapport with the respondent159
. A fourth possible explanation could be the way 159
By contrast, our study relegated questions related to income to the very end of the survey.
in which income data were extracted. The WTP survey initially intended to inquire about monthly income but opted to instead query respondents on income over the past six months to account for month-to-month variability in income for occupations such as subsistence farming. Providing estimates for such a long time frame may have proved difficult for some respondents, resulting in underestimates of income160
. Our survey queried respondents 160
Indeed, some enumerators reported that respondents struggled to estimate income [UNICEF and Administração de Infra-estruturas de Água e Sanea- mento,2012].
about income from a variety of sources including work, relatives’ contributions, remittances, social subsidies, etc. to ensure that totals reflected all forms of household income, and it allowed respondents to specify income according to their preferred time period161
for 161
Day, week, month, etc.
each of these sources of income to minimise recall bias.
Although any of these reasons may have come into play, the most likely explanation is sampling variability. For the WTP sur- vey carried out in2012,63.7% of households reported using rivers as their primary water points, and35% reported practicing some form of open defecation, both indicators of low SES. A more com- prehensive baseline survey carried out as part of NAMWASH in September and early October2012and including252households from Ribáuè produced drastically different estimates with under 5% of households using rivers as primary water points and under 10% reporting practicing some form of open defecation. These two surveys carried out as part of NAMWASH in2012also produced significantly different results in terms of preferred water infrastruc- ture with the original WTP study finding that48% of households preferred standpipes and25.1% preferred yard taps. The base- line survey carried out just three months later produced exactly the opposite results, finding that55.92% of households preferred yard taps, whereas only24.90% preferred standpipes. This would again be consistent with sampling of households with very different
socio-economic situations, as households with less income would likely be cognisant of the increased cost of a yard tap and so would state a preference for a standpipe.
The NAMWASH baseline survey carried out in September and October2012did not collect income data, but comparisons between that study and the study carried out in November2014are possible for key indicators such as water point and sanitation facility usage. Figures21and23show a comparison of primary water point us- age as reported by households for each of these surveys for Ribáuè and Liúpo, respectively. Due to the piped water infrastructure in- troduced as part of NAMWASH, there would be anticipated to be changes in primary water point usage from2012to2014, but totals are largely consistent with what would be expected based on base- line survey totals, and usage of river water was again significantly lower (under10%) than what was reported in the2012WTP survey. For reference, Liúpo was also included in the baseline survey, and results presented in2014are nearly identical to those reported in 2012, as would be expected for a town that did not benefit from any water interventions during the interim. Along the same lines, primary sanitation facility usage saw some changes in Ribáuè from 2012to2014due to NAMWASH, but levels of open defecation re- ported in2014continued to be more in line with what was reported under the baseline survey than what was reported under the2012 WTP survey, as evidenced in Figure30. These consistencies be- tween the baseline survey and our survey in November2014would suggest that the sample of households obtained for the2012WTP study is an anomaly, explaining the massive differences in reported income observed.