Slide 1: Note the lack of attribution for this photo, which I did take myself. It is normal (though incorrect!) behavior to re-use Commons photos without attribution. The same is true for data shared across projects. Wikidata simply centralizes (and augments!) such data where we can find it easily the way categories on Commons make it easy to find photos.
Slide 2: I want to talk about lists and ways that Wikidata lists help us curate information on Wikipedia. First we have 3 types of lists: Wikidata lists, WikiProject lists, and lists of things on sister projects, such as Wikipedia. Wikipedia lists are fascinating, but today all hand-crafted and quite tedious to translate into other projects. This presentation is an introduction to three types of Wikidata lists all created by User:Magnus Manske: Listeria, Dynamic Lists, and Autolist
Slide 3: The main thing to remember when using Wikidata lists is that all things you want to list must have items in Wikidata! Here is another photo I took this week and we are standing under a painting of David and Goliath. This painting now has an item Q21561211 because I created it afterwards and linked its image to this one. I can now access this painting from a list of paintings in the Royal Palace of Amsterdam. This photo (which still does not have its own item number) shows another painting at the very end of the hall, and I have not created an item for that one however. Wikidata is the work of volunteers, just like Wikipedia.
Slide 4: This slide shows one of many Listeria lists residing in my user space on the English Wikipedia. It is a Listeria list of paintings by Rembrandt. The Rembrandt Research Project is a Dutch concept, but if there is a museum off in South America or somewhere else that claims they own a Rembrandt and that Rembrandt is not in the list of paintings by the Rembrandt Research Project, then who are we to determine the attribution? All we can do is show the data. We can list the data we have on the Rembrandt Research Project and the data from the museum, and data on all of our image donations and other sources claiming Rembrandt attributions. I use the listeria lists to easily create lists for use in Wikipedia that update and sort on date of creation with a mouseclick. In the case of Jacob van Ruisdael I translated such a list into 4 languages.
Slide 5: This slide shows my Dynamic list of Rembrandt paintings in Horst Gerson's 1968 catalog Rembrandt catalog raisonné, 1968. The advantage of dynamic lists is that they reside on Toollabs and not on Wikipedia, where they may upset Wikipedians attracted by the many links in them. My list of Ruisdael paintings in the main namespace caused quite a stir in the German community and was deleted in disgust, but I am happy to see that my "userspace version" is allowed to reside on dewiki without comment. Dynamic lists update in real time as you change columns by adding or subtracting tracking properties. It is a great playground to get started with lists, outside of the projects.
Slide 6: This slide shows Autolist, which is where you need to test your queries. Here the query is "claim[170:5598] and claim[31:3305213]" which is for Property creator=Rembrandt and Property instance of=painting, or show me all paintings with Rembrandt as creator. The third column shows a blue-linked title of the sitelink in the language you are currently logged in with (here it is English). By adjusting the language code and downloading the results, you can use this tool to find candidates for the Content Translation Tool.
Slide 7: This slide shows how my Ruisdael list has been added to the Welsh Wikipedia by User:Llywelyn2000. I was particularly impressed by their use of the Q numbers to reference the rows of the list, and I have used their idea here. Adding Q numbers is helpful when the list items are not Wikipedia articles. The item has more structured data than the Commons files do, in this case and in the case of many paintings in the Wikiverse.