Barbara Gruehl Kipke

Bicycle Usage in Two Cities of Africa

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PROCEDURE OF RESEARCH - Sample Size

For reasons of handling and after consideration of the necessary sample size in order to obtain useful results it was decided to question approximately 120 households (i.e. approximately 480 individuals) in each city. It is expected to take six weeks in each city, in which the interviewers will be in groups of two and conduct one survey per evening.

The households will not be selected according to random sampling methods. Rather, quotas of households will be decided upon according to the stratified sampling approach. Half of the households interviewed will own one or more bicycles. The most important occupational groups, that are to be found in the lower income quarters, should be adequately represented in order to compare trip patterns and vehicle ownership in relation to occupation. Quotas are also created, by asking two adults and two children within each household when possible. The high percentage of young people corresponds to the age structure of tbe population.