Bi-COM Poisson Gaussian Copula Model for Clustering of Correlated Over- and Under- Dispersed Counts
Presentation by: Ms Saifa Raz, Research Associate, CPD
Ruan (2015) recently proposed using a finite mixture model with components modelled by Gaussian copula with Poisson margins (BP-GCD) as the basis for model-based clustering of bivariate correlated counts. Although the Poisson distribution is a useful model for modelling count data, the distribution is constrained by its equi-dispersion assumption. Motivated by this limitation, the thesis introduces a more flexible model, one with Gaussian copula models as components but with Conway-Maxwell Poisson (COM-Poisson) margins (BCOM-GCD) which allows the accounting of under- and over-dispersion in the correlated count data. We test our proposed method on a variety of simulated settings and on data from the Australian National Health Survey to explore the impact of ignoring the non-equidispersion. Our simulations and real-life data analysis indicate that using BCOM-GCDs as mixture components instead of BP-GCDs provides a better and more flexible approach for performing model-based clustering for under- or over-dispersed counts.
Will the Least Developed Countries be left behind?
The risks of a universal development agenda
Debapriya Bhattacharya and Sarah Sabin Khan
(The article was written for OECD’s forthcoming anthology on global risks)
Presentation by: Sarah Sabin Khan, CPD
The 2030 Agenda for Sustainable Development, adopted unanimously by 193 heads of state at the UNGA, made an expressed commitment to “leave no one behind” in the post 2015 development discourse. The article argues that progress of the least developed countries (LDCs) should be the metric for progress against this commitment given their highly marginalised situation even after 35 years of the category’s recognition. LDCs bore an average of 31% of global poor between 2003 and 2012 residing among only 12% of global population. Almost half of the 48 LDCs also fall under one or more other vulnerable category including LLDCs, SIDS, conflict-affected etc. The plight of LDCs are highlighted in this article by demonstrating trends in their poverty profile, geographical profile, non- convergence with developed countries, growing inequality, decreasing share in world trade and lack of diversification, and declining resource inflows. LDCs are further disproportionately exposed to challenges as far as repercussions of conflicts, slowdown of global economy, commodity price shocks and climate change are concerned. The paper concludes by suggesting three policy perspectives- fulfilment of commitments by international development partners in terms of aid and trade access; combating systemic risks through policy and institutional coherence; and domestic reforms.