In an international comparative study of self-help transformations (alterations and extensions) to government-built housing in developing countries, sponsored by the Overseas Development Administration, data were collected on household and housing characteristics of about 400 households in each of four case studies (in Dhaka, Bangladesh; Cairo, Egypt; Kumasi, Ghana, and Harare, Zimbabwe). The data for each country have been used in a two step econometric analysis of the decision to transform.
The first step examines the factors which influence the decision to make an extension in the period 1991-93 (the three years before our survey) and the second step examines how much is spent on the extension. The data from all four case studies are also combined in a joint model.
In general, it seems that characteristics of the house are very influential in the
decision to transform and in the decision on how much to spend once the
transformation has been undertaken. Thus, the frequency and scale of extension activity by low income households in developing countries could be influenced by physical planning policy.
Urban Studies (2000) 37 (9): 1605-17. pp. 23