Not everyone is able to look at a graph and immediately understand the messages, so it is useful to be able to summarise what the indicator measures tell us. To highlight whether or not things are moving in the right or wrong direction, a set of traffic lights is used:

Green = clear improvement
Amber = little or no change
Red = clear deterioration
Missing = insufficient or no comparable data

The traffic lights are determined by comparing the measure in the latest year with its position in an earlier base year – in most cases 1990 and 2003.  Between the base year and current position the measure may have deteriorated and then improved, or vice versa.  However, the traffic lights only reflect the overall change in the measure from the base year to the latest position and do not reflect fluctuations during the intervening years.

Some of the issues covered by the indicators are complex and cannot be described using one single measure, so some of the indicators are comprised of more than one component measurement, and in all there are 126 assessed indicator measures making up the 68 indicators.

Pie chart summaries

It is not practicable or meaningful to combine all 126 disparate indicator measures into a single index of sustainable development.  Aside from the technical difficulties involved, some indicator measures are more important or challenging than others and key messages would be lost.

However to gain some indication of the extent to which overall change is in the right or wrong direction, it may be informative to quantify the number of traffic lights that are  green, amber or red across the indicator measures.  This approach forms the basis of the ‘pie-chart’ summaries.

The pie charts show the accumulative traffic lights for all 68 indicators and separately for four themes.  A number of indicators are relevant to more than one theme, so there is some overlap in the measures summarised in the pie charts.

Indicator measures do not contribute to the summaries if (a) they are used in another indicator and are already counted within the same summary; (b) their trends are strongly influenced by or directly reflect other measures within the same summary; or (c) they are for contextual purposes.

Presentation of the indicators

For each indicator, one or more charts are provided that show the data from 1990, or the earliest available year after 1990.  In many cases a small chart additionally will be shown within the main chart to illustrate the longer-term change – going back as far as 1970 if data are available. The presentation of the charts has been simplified as far as possible.  For example on the x-axis not all years for which data are presented have been indicated.

The indicator measures may be shown as an index, which means that the value of the measure for a base year, mainly 1990 (and 1970 for the small longer-term charts), is treated as representing 100 (per cent).  Subsequent or preceding values of the measure are then shown in relation to that base value – in effect as a percentage of it.  This allows trends in measures with different units to be more easily compared.

The traffic lights assessments are shown beneath the charts.  If trends in individual measures are moving in the same direction then for ease of presentation traffic lights may be shared, although the measures will have been assessed individually.

A short statistical commentary on the indicator is then provided to highlight and explain the trends and assessment.

Change in methodology

Prior to Sustainable Development Indicators in Your Pocket 2009, two baseline years of 1990 and 1999 had been used to summarise the direction of change in the indicator measures, using ‘traffic lights’.

When the two baselines were established in 2005 the aim was that the 1990 baseline would provide a long term assessment of progress, whilst the 1999 baseline would provide an assessment of recent changes. However the 1999 baseline is no longer sufficient for a short term assessment, hence the short term baseline will be revised and progress will be assessed using 2003 as the baseline instead of 1999, whilst still retaining the 1990 baseline.

2003 is the latest year from which it is practicable to make a consistently robust assessment of change across the indicators.

A summary of the traffic lights using the 1999 baseline were provided as an annex in the 2009 publication.

Page last modified: 30 March, 2011

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