270 likes | 447 Views
CONCEPTUAL ISSUES IN CONSTRUCTING COMPOSITE INDICES. Nadia Farrugia Department of Economics, University of Malta Paper prepared for the INTERNATIONAL CONFERENCE ON SMALL STATES AND ECONOMIC RESILIENCE Organised by The Islands and Small States Institute
E N D
CONCEPTUAL ISSUES IN CONSTRUCTING COMPOSITE INDICES Nadia Farrugia Department of Economics, University of Malta Paper prepared for the INTERNATIONAL CONFERENCE ON SMALL STATES AND ECONOMIC RESILIENCE Organised by The Islands and Small States Institute of the Foundation for International Studies at the University of Malta and the Commonwealth Secretariat, London Valletta, Malta 23 - 25 April 2007
Presentation Outline • Introduction • Desirable Attributes for Developing Statistics and Composite Indices • Main Conceptual Issues • Indicator Selection • Dealing with Missing Data • Normalisation • Weighting and Aggregation • Testing and Reviewing the Results Obtained • Conclusion
Definition • A composite index, • is a weighted (linear) aggregation of a number of variables • wj is a weight, with 0≤wj≤1 and ∑wj=1 • Xcj is the variable of country c in dimension j • for any country c the number of policy variables are equal to j=1,…,m.
Uses • Describe complex phenomena in a single indicator • Cross-national comparisons of country performance • Benchmarking exercises • General trends • Policy priorities and performance targets • Several examples of renowned composite indices, stock market indices, RPI, GDP
Strengths • Summarises complex and multi-dimensional issues • Helps set the direction for policymakers and to focus the discussion • Supports decision making • Helps disseminate information • Make stakeholders and the public more aware of certain problems • Generates academic discussion
Weaknesses • Subjectivity in computation • May send misleading policy messages and can easily be misused • May conceal divergences between different components • Increase difficulty in identifying proper remedial action • Measurement problems
Quality Frameworks • IMF – Data Quality Assurance Framework • Eurostat Framework • OECD – Quality Framework and Guidelines for OECD Statistics • Booysen – Dimensions for Classifying and Evaluating Development Indicators • Briguglio – Desirable Characteristics for Developing Vulnerability Indices • JRC-OECD – Handbook on Constructing Composite Indicators
Desirable Attributes of Composite Indices • Accuracy • Simplicity and Ease of Comprehension • Methodological Soundness • Suitability for International and Temporal Comparisons • Transparency • Accessibility • Timeliness and Frequency • Flexibility
Main Conceptual Issues • Indicator Selection • Dealing with Missing Data • Normalisation • Weighting and Aggregation • Testing and Reviewing the Results Obtained
Indicator Selection • Define the concept • Select indicators which satisfy desirable attributes • Do not select variables which beg the question • Draft an initial indicator set and review the available data • Keep the number of variables as small as possible but not fewer than necessary (PCA, FA)
Indicator Selection (Cont.) • Check for correlation between the variables or sub-indices (rank correlation test, Cronbach coefficient alpha, cluster and discriminant analysis) • Review the indicators selected and seek external advice and opinion
Dealing with Missing Data • Exclude the country from the analysis • Imputation methods: Single or Multiple
Single Imputation Methods • Case deletion • Mean/median/mode estimation • Hot deck imputation • Regression imputation
Multiple Imputation Methods • Regression Method • Propensity Score Method • Markov Chain Monte Carlo Algorithm
Quantifying Qualitative Data • Using a mapping (Likert) scale • Optimal spread of the scale • Permits non-linearity • Defect relates to subjectivity
Normalisation • Rescaling • Standardisation (or z-scores) • Percentage differences over previous years • Ratios • Rankings • Measuring the relative position vis-à-vis a specified point
Weighting and Aggregation • Equal Weighting • Differential Weighting • Country-Specific or Indicator-Specific Weights • Weights Over Time: Constant or Changing
Differential Weighting • Weights Reflecting the Statistical Quality of the Data • Stochastic Weights • Participatory Methods • Precautionary Principle • Regression Method • Benefit-of-the-Doubt Weighting System
Aggregation • Linear or geometric aggregation • Aggregation methods and weighting systems • Non-compensatory multi-criteria aggregation
Testing and Reviewing the Results Obtained • Uncertainty and Sensitivity Analysis • Outliers • Expert Opinion • Analysing the Results Obtained
Conclusion • Composite indices have their pros and cons. • Hard to imagine that the debate on the use of composite indices will be ever settled. • Composite indices should be identified for what they are. • However, their importance should not be undermined. • Provided they are built on sound methodological considerations they are very useful to portray complex phenomena in a simple manner.
Thank you! farend@onvol.net