LITERATURE REVIEW
2.2 Concepts of space, distance and accessibility
Space is a relation defined on a set of objects (Gatrell, 1991). The concepts of space can be divided into physical space and relational space. Physical space is the relation defined on a set of objects that is largely defined by physical factors influencing the relationship between the objects. Physical space can be measured using quantitative metrics. Physical space is further divided into absolute space and relative space.
Absolute space can be conceptualised by a straight line drawn between pairs of objects.
Absolute space is continuous and cannot be changed by any matter or energy (Abler
et
al., 1971).
The metric for measuring absolute space is absolute distance. Absolute distance is also referred to as Euclidean distance (Gatrell, 1991). The metric units for measuring absolute distance are miles or kilometres. Absolute distance has been a major consideration in health care planning and health facility placement in developing countries and sub-Saharan Africa. This is based on the assumption that most people in these countries access health facilities on foot. Another assumption is that people use their nearest health facility (Joseph & Phillips, 1984; Phillips, 1990).
Relative space represents physical realities and can be defined as a relation on a set of objects relative to human activity. Therefore, relative space changes, (shrinks or stretches) depending on intervening obstacles such as traffic, mountains or social interactions (Abler
et
al., 1971). Measurements of relative distance have been necessary to measure distance
relative to human activities since Euclidean distance does not take into account barriers or intervening obstacles. Examples of physical factors that might influence accessibility of clinics would be topographical barriers like mountains or valleys between the objects or the presence and quality of transport services between the objects.
Manhattan space or 'taxi-cab' distance and Riemann space are two forms of relative space.
In Manhattan space, the shortest distance between two points is a path consisting of line segments, which meet at right angles. This space shows that in the city of New York (as in other cities) actual distance travelled is not the shortest distance between two points, but it is dependent on the roads, which travel around blocks of buildings. Distance within Manhattan space can be measured in terms of overcoming difficulty of going around the blocks, that is, the time or cost spent to achieve this task. The time will be longer (stretched) or shorter (shrunk) depending on the density of the traffic (Abler et al., 1971).
Riemannian space is measured in the same way as Manhattan space, except that the shortest distance between two pOints is a curved line, for example, a route around a mountain. While the concept of Manhattan space applies mainly to urban areas and to people utilising transportation, the concept of Riemannian space would be more applicable to rural areas where there are rivers or mountains to overcome before reaching destinations. However, people who travel on foot particularly in rural areas, use the shortest and quickest possible routes between homesteads and clinic i.e. footpaths, which follow contours, negotiate topography and avoid obstacles.
For the purpose of this thesis, this form of relative space will be called footpath space.
Footpath space is useful for understanding the movement through rural areas where people do not always travel in straight lines. For example, instead of going out of the kraal of the homestead through the main entrance, rural people would choose to go through an opening in the kraal or pass through their neighbour's yard. Footpath distance is thus an appropriate metric for measuring accessibility of clinics in rural areas. The metric for measuring relative space is relative distance and can be measured in monetary or time units such as Rands and minutes. Time and cost are said to be far more powerful determinants of accessibility than are absolute distances and they are thus better explanatory variables of spatial
behaviour (Phillips, 1990). However, measurement of time is very complex, laborious and expensive (Perry & Gesler, 2000). In South Africa, MCH services are offered free of charge at the clinics in rural areas. For these reasons, measurement of time and cost will not form part of the analysis in this study.
Relational Space is a relation defined on a set of objects that is defined by macro- and micro-environmental forces which may be political, social, economic, cultural or environmental in nature, and which are measured using qualitative methods. An example of how these forces might influence accessibility of clinics in relational space would be the effect of political conflict between the African National Congress and the Inkatha Freedom Party in certain parts of the province on clinic services and the ability of clients to use those services.
This political allegiance and the location of a clinic in an area of a particular political dominance would be the relation that binds the homesteads and clinics together. Examples of micro-environmental forces operating in relational space would be the socio-economic status of clients (ability to pay) or the competency of clinic nurses. Relational space will not be discussed further in this thesis since it is not the intention of this study to examine health service utilization and health status in a relational space. However these complex forces in relational space may be very important determinants of accessibility in many rural areas.
Since this study attempts to understand the relationship between accessibility and health care, the researcher has decided to employ absolute distance that separates health service providers and consumers, as a surrogate measure of accessibility. For the purpose of this study, accessibility refers to the ability of an individual to obtain health services within reasonable reach and would include both absolute and relative distance (UNSD, 1997).
In this thesis absolute distance is used to refer to physical distance that separates homesteads and PHC facilities. The phrase 'other factors of accessibility' such as age, sex, educational level, parity, transport, cost and time is used to refer to relative space. The term physical accessibility is used interchangeably with absolute distance. Section 2.3 provides a brief introduction of the methods and techniques that are used to measure spatial relationships in the context of health care.