Chapter 4. Methodology
4.3. Indicators for the chosen criteria and development of value functions
4.3.2. Financial and technological indicators
figure for Nitrogen, Phosphorus and Potassium is 5.5kg in South Africa.
unlikely to reach 100% a figure of 5
the allocation of rating values to rounding to the nearest kilogram. The recommended value organic matter offers a similarly simple transformation (
Since the environmental indicators are continuous variables, these will be entered as raw scores rounded to the nearest integer in the range described in
scores between 0 and 5 shown to 2 decimal places in the MCDA.
unlikely if waterborne sewerage is added to the MCDA. Edwards and Newman (1982, p.67) assert that the boundary values chosen should be “minimum and maximum pl
minimum and maximum possible, conceivable, or actual values”.
Minimum and maximum values for the Operations and Maintenance cost criterion were set at R0/person/ year and R1 200
sanitation of Rosemarin et al to 2012 values).
Standardisation of these financial indicators was monetary scale is already
value of 5 was assigned to the minimum v linear function with a negative gradient.
Durability was measured as life expectancy in years, with 50 years as a maximum (the design life estimated by Schuen and Parkinson
life expectancy does provide an ideal situation, but a linear
criterion. While system lasting 1 year is fairly undesirable, 20 years is an excellent lifespan for on site sanitation and was hence rated as 4 on the standardised scale. The value function for durability is illustrated in Figure 4-4
considered and effectively this becomes analogous to a qua
unlikely if waterborne sewerage is added to the MCDA. Edwards and Newman (1982, p.67) assert that the boundary values chosen should be “minimum and maximum plausible values, rather than minimum and maximum possible, conceivable, or actual values”.
Minimum and maximum values for the Operations and Maintenance cost criterion were set at and R1 200/person/ year (a compromise between the estimate
of Rosemarin et al., 2008 of R125 and Holden et al., 2004 of R1 910, both costs adjusted
Standardisation of these financial indicators was performed using a linear transformation since a monetary scale is already interval scaled and compensatory. Since lower cost is more desirable, a was assigned to the minimum value and 0 to the maximum value, hence producing a linear function with a negative gradient.
Figure 4-4. Value function for “Durability”
Durability was measured as life expectancy in years, with 50 years as a maximum (the design life and Parkinson (2009) for sewerage and treatment infrastructure). This longest expectancy does provide an ideal situation, but a linear function seems inappropriate for this criterion. While system lasting 1 year is fairly undesirable, 20 years is an excellent lifespan for on site sanitation and was hence rated as 4 on the standardised scale. The value function for durability
4. Since this is likely to be an estimated value, no values in between are considered and effectively this becomes analogous to a qualitative variable.
unlikely if waterborne sewerage is added to the MCDA. Edwards and Newman (1982, p.67) assert ausible values, rather than
Minimum and maximum values for the Operations and Maintenance cost criterion were set at a compromise between the estimates for waterborne 2004 of R1 910, both costs adjusted
using a linear transformation since a interval scaled and compensatory. Since lower cost is more desirable, a to the maximum value, hence producing a
Durability was measured as life expectancy in years, with 50 years as a maximum (the design life (2009) for sewerage and treatment infrastructure). This longest function seems inappropriate for this criterion. While system lasting 1 year is fairly undesirable, 20 years is an excellent lifespan for on- site sanitation and was hence rated as 4 on the standardised scale. The value function for durability
. Since this is likely to be an estimated value, no values in between are litative variable.
Table 4-4. Indicators and scaled indicator values for financial and technological sustainability Criterion Indicator/ range Scale
Robustness: ability to withstand abuse, ease of construction, simplicity of design,
qualitative 0= susceptible to misuse, challenging construction, advanced technology.
1 = more robust, challenging construction, advanced technology.
2 = robust, challenging construction, advanced technology.
3 = robust, challenging construction, simpler technology.
4= robust, simpler construction, simpler technology.
5= robust, simple to construct, simple design Requirement for
outside intervention, requirement for monitoring to ensure appropriate disposal of waste
qualitative 0= monthly intervention 1= six-monthly intervention 2= annual intervention 3=intervention every 2 years 4= intervention every 5 years
5= intervention every 10 years or more Durability: life
expectancy of system years 1-50
0=1 year 1=2 years 2=5 years 3=10 years 4=20 years 5=50 years Construction cost:
materials, labour, institutional requirements
R/household 500-15 000
0= 15 000 1= 12 100 2= 9 200 3= 6 300 4= 3 400 5= 500 Cost of O & M:
repairs, servicing (e.g.
emptying)
R/person/ year 0 – 1 200
0= 1 200 1= 960 2= 720 3= 480 4= 140 5= 0
Criterion Indicator/ range Scale Employment: jobs
created by construction and maintenance
qualitative values are approximate
0=no jobs created / 1 000 households 1=1 new job created/ 1 000 households 2=5 new jobs created / 1 000 households 3=10 new jobs created/ 1 000 households 4=15 new jobs created/ 1 000 households 5=20 new jobs created/ 1 000 households Local
development: promoti on of local business in construction and maintenance
qualitative 0=All construction and maintenance by international agency
1=Some international assistance, national construction agency
2=National and regional agencies 3=All regional construction, O&M 4=Some local community, some regional construction and O&M
5=All construction and maintenance performed within the local community
The remaining indicators were also considered to be qualitative. In describing the different levels an attempt was made to make the underlying rationale for including the criterion explicit. This was so that when a new sanitation option is added to the MCDA, the basis for comparison is clear. As an example the criterion “Requirement for outside intervention” was described by the scale: 0:
monthly intervention, 1: six-monthly intervention, 2: annual intervention, 3: intervention every 2 years, 4: intervention every 5 years, 5: intervention every 10 years or more. Effectively the numbers are simply there to make it easier to assign a value to an option than terms such as “frequent” or
“seldom” and not as exact numerical measures. There would be no non-integer values assigned and a process of approximation would assign values to different systems. Similarly, job creation has figures assigned to the different ratings, but these are intended as a guide only.
Some criteria incorporate some different aspects of the central concept. Robustness is intended to cover the ability of the system to withstand misuse, but also the complexity of design and construction. The performance of these different aspects is described as the indicators are developed. Thus an option must be robust, simple in design and easy to construct if it is to score 5 on the scale.