The International Tokamak Physics Activity Topical Group on scrape-off layer and divertor physics has amassed a database comprising hundreds of reciprocating Langmuir probe measurements of the main scrape-off layer heat-flux width in inner-wall limited discharges. We have carried out an analysis, based on turbulent transport theory, of the variation of with respect to the dimensionless plasma parameters. Restricting our analysis to circular plasmas, we find that a model based on non-linearly saturated turbulence can well reproduce the values found in the database.