3.7 Sampling
The sample population was obtained through both simple random and convenient sampling (Figure 2). All main roads (Morogoro, Kilwa, Nyerere and Bagamoyo) from the city centre that directly connect Dar es Salaam to the nearby region (Coast Region) were included. These roads represent Dar es Salaam by the fact that each district of Dar es Salaam region has at least one of these roads.
All commercial motorcycle parking points along those roads to the geographical boundary with Coast Region were mapped and assigned a specific identity. The mapping process was done by the principal investigator and one commercial motorcyclist familiar with the concerned road.
For each road, two categories of commercial motorcycle parking points, those within the city (urban), and those outside the city (peri-urban) were made. For each category, the commercial motorcycle parking points to be included in the study were obtained by using the table of random numbers. Commercial motorcyclists from the selected parking points were conveniently included in the study.