There is a general expectation that open government data (OGD) can lead to the generation of value for government, business, and society. However, there appears to be a lack of scholarly literature that empirically validates what this value is or how it emerges. This paper addresses this concern by exploring what empirical evidence currently exists about the effects stemming from OGD in the case literature. Through the use of a literature review, 17 papers capturing empirical evidence were identified and, from these papers, a systematic collection of statements was extracted from which 173 were retained to construct what we term nine stylised facts. The identified stylised facts depicting features and correlations provide some insights into the de facto positive, negative and/or inconclusive effects relating to OGD as opposed to simply opinions and beliefs.