A RECENT article took issue with the Tasmanian government for not conducting an independent study of the economic benefits of allowing same-sex couples to marry.  I co-authored the study cited that estimates Tasmania would gain nearly $100 million in business spending if it were the first state to allow marriage for same-sex couples, and I presented this study to Premier Lara Giddings when I met her in February. Our study is not only independent but provides a credible and conservative estimate of the gains that the state's wedding-related businesses would experience. The study for Tasmania is one of the latest by our university- based research institute. The Williams Institute at the UCLA school of law is an independent organisation that conducts research and analysis on sexual orientation and gender identity issues. Policymakers in the US and other countries have commissioned and used our research. Our work appears regularly in peer-reviewed academic journals because we use high-quality data and rigorous methods. We have conducted numerous studies of the economic impact of marriage at the request of policymakers in the US. Our methods for projecting the effect of same-sex marriage have been adopted by other research organisations. The figures used in our projections have been borne out in data collected after same-sex couples have been able to marry. As a general practice, our estimates are deliberately conservative. In this case that means that we used low estimates of the number of same-sex couples who would travel to Tasmania and low estimates of how much they might spend. A different study commissioned by the government might well estimate much larger gains for the Tasmanian economy.