Usability Testing for an IGO
A website for a large government data agency to connect the policymakers, advocacy groups and academics with UNESCO data for their Sustainable Development Goals for the purposes of research and advocacy.
They already had a prototype that they wanted to test. It was a new WordPress Theme, with a different layout, streamlined content and added navigation. In addition to the discovery of any general usability problems of the new layout, the navigation and ease of finding things was singled out as a priority.
If it were just the nav, I would have chosen tree testing but because we were also interested in usability of the pages themselves so I went with usability testing, but integrated some tree testing-esque metrics.
The reason I didn't go with A/B testing was because there were no real "conversions" to be had, and we also wanted qualitative data.