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3.2 Location and Proximity Measures
I used confidential datasets in order to track households as they moved. 26 I used original enumeration
areas maps to locate the original living location of households in the first wave of
the sample, then used household addresses from survey tracking sheets to update household
locations as they moved.
I used ArcGIS maps of the original EAs sampled to map the approximate locations of the
households at the start of the survey. I then used household’s addresses in later waves, transcribed
from the survey documents, to identify households that had changed address. I then
geocoded the new addresses. In this way I tracked households throughout the four waves by
their GPS coordinates. 27 I was then able to generate a range of distance and geographic outcomes
for each household. In each wave of data I calculated the distance from schools, roads,
the city centre, and the distance of move from the original place of living at the basline (if there
was any move at all).
Summary statistics of the migration data are presented in table 2, along with the housing
distance data described in the next section. Roughly 30% of the sample moved at some point
during the survey. 28 The average move distance is small, under 1 km. 29 This data gives an idea
of how far informal households live from the city centre- 26kms on average.
Table 2: Proximity data in wave 3 (2006)
Mean Min Max N Control Treat Diff
City Distance 25.8 4.05 53.3 968 24.7 27.8 3.07***
School Distance 0.48 0.019 3.43 970 0.50 0.45 -0.041
Moved 0.36 0 1 970 0.34 0.40 0.060
Move distance 0.94 0 36.8 970 0.95 0.92 -0.025
Cumulative dist moved 1.53 0 36.8 968 1.37 1.83 0.46
Distance Proj1 0.88 0 16.7 970 1.13 0.41 -0.73***
Distance Proj2 2.41 0 28.6 970 2.82 1.69 -1.13***
Distance Proj3 3.24 0.046 31.2 970 3.60 2.57 -1.04***
Rank Proj1 0.39 0 1 970 0.35 0.48 0.13***
Rank Proj 2 0.11 0 1 970 0.089 0.16 0.068***
3.2.1 Housing Project Distances
Most importantly I was able to generate distances for each household, in each wave, to all of the
government housing projects on which houses had been constructed during the years since the
last survey. For the reasons that become clear in the next section, I focus only on the distance
between housing projects and enumeration areas (EAs) that the household was living in the first
26 These were provided with the help of Jeremy Seekings of the Centre for Social Science Research, University of Cape
Town, and David Lam of Population Studies Center, University of Michigan, after discussions in January 2011.
27 I used Google maps for this. Their batch geoprocessing tools could not always be used because of the considerable
variation in spellings of streets and areas name, especially when in different languages, or in newly developed areas
were street names had not been formalized. Most of these GPS coordinates had to be found by hand.
28 Most of these moves were within the boundaries of the City of Cape Town, but there were a few households that
moved back to rural areas in the Eastern Cape or KwaZulu Nata, some hundreds of kilometers away. For the purposes
of urban relocation analysis, such outliers were excluded from the sample.
29 This may be an underestimate because households that moved further were less likely to be found, and there were
sometimes mistakes with updating address data during the fieldwork.
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