I wish the page had a short explanation on how the bubble index was calculated.<p>From the PDF:
<i>The Index score is a weighted average of the following five standardized city sub-indices: priceto-income and price-to-rent (fundamental valuation), change in mortgage-to-GDP ratio and change in construction-to-GDP ratio (economic distortion) and relative price-city-to-country indicator. The price-city-to-country indicator in Singapore and Hong Kong is replaced by an inflation-adjusted price index. The approach cannot fully satisfy the complexity of the bubble phenomenon. We cannot predict if or when a correction will happen. Hence, “bubble risk” refers to the prevalence of a high risk of a large price correction.</i>