Step 7 – comprehensive accessibility score

The final step in the process involves combining each of the six age group composite accessibility scores into a single value that measures the overall accessibility for the site.

This is performed separately for places of employment and the seven consumed activities, forming an employment and consumed comprehensive accessibility score respectively.

Two more weighting matrices are used to weight the scores from each of the age groups when aggregating the values into the respective comprehensive accessibility scores (A).

For the generic activities the weighting apportioned to each of the six age groups is set to the age group’s proportion of the national population at the time of the most recent census (2006). For places of employment, the population is weighted based on its fraction of the population aged 10 and over (to represent the working population). The population counts from the 2006 Census and their proportions are presented in table 15.3.

Table 15.3    Age group weightings from 2006 Census data

Age group

National population count (2006 Census*)

Weighting
(generic facilities)

Weighting
(places of employment)

0–4

275,079

0.07

0.00#

5–9

286,488

0.07

0.00#

10–19

606,207

0.15

0.18

20–24

270,978

0.07

0.08

25–64

2,093,589

0.52

0.60

Over 65

495,606

0.12

0.14

Total

4,027,947

1.00

1.00

The weightings applied to each age group (right column) were calculated based on each age groups population (middle column) as a percentage of the total population (or working population – approximated as those aged in the 10–19-year age bracket and over.

#Age group outside those considered to contain working age individuals.

*2006 Census data, Statistics New Zealand (2007)

 


This weighting matrix was used with the six age group composite accessibility scores in the following equation to generate the respective comprehensive accessibility score (A). This score calculates the overall accessibility of the seven consumed core+ activities from the measurement location to form the consumed comprehensive accessibility score.

 

Using the same equation, but substituting the weightings for places of employment (shown in table 15.3) yielded the employment comprehensive accessibility score.