Methodology

Sovereign Bond Markets

Diebold-Yilmaz Connectedness Index (DYCI) methodology is applied to daily 10-year government bond return volatilites in 12 major economies over the period from January 4, 2000 through August 11, 2015. The results are based on generalized variance decompositions (with 10-day forecast horizon) obtained from a VAR(3) model of daily range volatilities. The VAR model is estimated using the elastic net shrinking and selection procedure, which combines Lasso and Ridge estimators.

Dynamic connectedness measures are obtained from the estimation of the VAR model over 150-day rolling windows. "Index" is the total connectedness measure. "To," "From" and "Net" are the "to," "from," and "net" directional connectedness measures calculated for each variable in the analysis.

Network graphs are created with Gephi (https://gephi.github.io/) open-source software for visualizing large scale network graphs. Node locations are determined using the ForceAtlas2 algorithm of Jacomy et al. (2014) as implemented in Gephi.

Node size indicates the country's government debt to GDP ratio. Node color indicates the "to" connectedness of the bond return volatility and varies according to the following color spectrum:

Edge thickness indicates the average weight, which happens to be the pairwise directional connectedness. In order to obtain a clear graphical image, we dropped the lower half of all edges after ordering them by their weights. Edge color does not vary with edge weight.

2014 by Francis X. Diebold and Kamil Yilmaz