deficiencies in infrastructure (lack of water, sanitation, and/or electricity), HHs that are built with inadequate materials (walls, roofs, and floors), and HHs that are overcrowded (e.g., Cristini and Moya (2008) cited in Lora et al. (2010); Szalachman 2000). Some authors expand this definition adding aspects such as insecurity of tenure (e.g., Habitat 2016), telephone coverage (e.g., Lora et al. 2010), or location and accessibility to markets (e.g., Acolin & Green 2017; Isalou et al. 2014). Others proxy the qualitative housing deficit by focusing on one qualitative aspect only such as access to drinking water (e.g., Gilbert 2001; ECLAC 1996). Yet another alternative to estimating the qualitative housing deficit is to survey HHs’ satisfaction with their homes. Gallup recently conducted such a perception-based survey asking respondents about their satisfaction with the availability of good, affordable housing. The results highlight a wide gap in satisfaction levels across countries which reflect the diversity of housing markets across the world (Gallup 2021).

These varying definitions and approaches towards the qualitative and quantitative housing deficit are particularly problematic when comparing deficit numbers. Diverging definitions of adequacy lead to different estimation methodologies of housing deficits and therefore render the comparison of housing deficits across studies meaningless. This becomes particularly apparent with the varying scope and number of qualitative dimensions considered to contribute to the qualitative housing deficit across studies. In particular, the aspect of overcrowding is ambiguous. It is sometimes considered to be contributing to the qualitative housing deficit, the quantitative housing deficit, or to both. A recent World Bank study regarding the housing deficit in Peru, for instance, highlights the impact of varying adequacy definitions. The study shows that the qualitative housing deficit equivalent to 23 percent of the country’s housing stock could rise to 68 percent when a stricter definition of housing adequacy is applied (World Bank et al. 2021: 26).

Based on their respective definitions, there are numerous within-country studies on the housing deficit. These studies focus predominantly on the mismatch between housing demand and the estimated existing dwelling stock for a particular country or several cities (e.g., Bower et al. 2019; Olaya et al. 2017; Szalachman 2000; UN Habitat 2011; Yoshino & Helble 2016). Different studies come to different conclusions as to how many housing units are missing – even for the same country. UN-Habitat’s _Ghana Housing Profile_ , for instance, compares different deficit calculations for Ghana, identifying eight distinct estimations within the literature, which range between 250,000 and 1.5 million housing units depending on the sources used and the definition and calculation method applied (UN-Habitat 2011). Similarly, in several studies on Indonesia, housing deficit estimations range between 3 million and 14 million missing units (for a critical overview on the several methodologies: Monkkonen 2013). The absence of a common definition, a transparent and uniform methodology to estimate deficits, and the missing distinction between