Methodology

1. Remove economies that have data for less than or equal to 12 indicators (60 per cent of all indicators). After the removal, a certain number of economies are included in the calculation below.
2. Some indicators (e.g., labour productivity) are converted to a logarithmic scale. This conversion can be justified by the existence of diminishing returns to scale of these indicators for sustainability objectives.
3. For some indicators (e.g., time in ports), extreme values are censored, with lower and upper bounds determined by 5th and 95th percentiles. All values below the lower bound are replaced by the lower bound, and values above the upper bound are replaced by the upper bound.
4. As the twenty indicators have different units and scales, they are rescaled to ensure comparability across indicators, using min-max normalization, i.e., x^'=(x-min⁡(x))/(max⁡(x)-min⁡(x)). The normalized indicators take values from 0 (i.e., the lowest value in the world) to 1 (i.e., the highest value in the world). 
5. For some indicators (e.g., road injury death rate), the normalized indicators are inverted, i.e., x^''=1-x^', to ensure that low values indicate poor performance and that high values mean good performance. 
6. The normalized indicators are aggregated by the following three steps: 
       i. Normalized indicators are aggregated within SFT categories (e.g., infrastructure, transport productivity) with equal weight on each indicator. This gives scores at the SFT category level; 
       ii. The scores at the SFT category level are aggregated within the SFT three pillars (i.e., economic, social, and environmental) with equal weight on each SFT category. This gives scores at the SFT pillar level. Before the aggregation, if scores at the SFT category are missing for a particular economy, the missing values are replaced by the regional average;
       iii. The scores at the SFT pillar level are aggregated to the overall score. 

As indicated by the list of indicators below, the coverage of the internationally comparable indicators is relatively limited. Such indicators do not exist for many social and environmental pillars. Further, some indicators are only available for the entire transport sector (e.g., labour productivity in the transport and storage sector). Also, some other indicators only cover a specific transport mode (e.g., road injury death rate). 

To overcome these limitations, information from local sources such as existing policy documents and studies as well as stakeholder surveys and interviews will be relied upon to complement the SFT Index in UNCTAD SFT rapid assessment.