The control variables included in the multivariate regression model besides our environmental performance (EP) measures have been documented to be causes of voluntary disclosures in the disclosure literature.We include them to avoid a correlated omitted variables threat that EP is standing in for some other well known determinants of disclosure in other disclosure channels. We divide the control variables in three groups: variables that proxy for the benefits of voluntary
disclosures, variables that measure costs of voluntary disclosures and other control variables.