D.1 For each sector, a performance and a cost index has been constructed. The performance indices are each based on an array of several dimension indices, which describe broad characteristics of performance. The dimension indices are constructed from quantitative indicators which describe particular elements of the performance of a sector.
D.2 The calculation of a performance index followed three steps:
• Indicators: Each individual performance indicator was first expressed as an index with the value for 2005 used as a base. 2005 was used as the base year because consistent time series across the sectors are only available as far back as that year. By using indices, the information conveyed by the indicators was expressed in relative terms, thus eliminating the effect of using different units for each indicator. All indices were constructed so that a growth in the index shows an improvement in performance. That is, for those indicators where a lower value indicates a better outcome (e.g. road fatalities), the index was calculated so that a fall in the value of the indicator (e.g. fewer road fatalities) is shown by an increase in the value of the index.
• Dimension indices: The indicator indices were then used to derive dimension indices. When several indicators existed for a given dimension, an arithmetic unweighted average was calculated to derive the value of the dimension index.
• Performance index: Once all dimension indices for a given sector had been calculated, an arithmetic unweighted average of these indices was used to derive the performance index for this sector.
D.3 The construction of the cost indices follows a simplified version of this method, as there are no cost dimensions. Costs figures were first expressed in real terms (either 2010 or 2009-10 prices depending on whether the underlying data was in calendar or financial year basis) before deriving an index. Cost indices have been built in such a way so that a growth in the index indicates higher costs.
D.4 As a general rule, annual data in the form 200x-200x+1 was ascribed to the year 200x+1.
D.5 67 performance indicators and 20 cost indicators were used in total across and 10 sectors. The figure D.1 below provides a summary of the dimensions included in the analysis of each sector.