I think there are two parts to the problem of filling gaps. Drawing attention to the gaps is half of the problem. The other half of the problem is finding the editor who wants to write that article. For example, I often check on the "missing topics" list for WikiProject Queensland (which is machine-generated by counting the number of redlinks in articles tagged on the Talk page as belonging to that project). https://en.wikipedia.org/wiki/Wikipedia:WikiProject_Queensland/Missing_topi… This is not a highly sophisticated algorithm but it does result in my thinking "oh well, I am sure I could at least write a stub on that topic" and so I write an article. But if you look at the first couple of screens of those "most missing" topics, there are lots of racing car drivers. I have no interest whatsoever in racing car drivers, I have no idea what sources might exist or which might be reliable. So as I pick off other topics from the "most missing" list, it has the effect of increasing the density of racing car drivers at the top of the list. Clearly we have a content gap around racing car drivers, but I won't be doing anything about it. This reinforces the point Leila makes about personalising the recommendations. I think it's more important to target the right people even if the list you present to them isn't overly sophisticated. The right person will be able to mentally filter a list of things vaguely associated with their topic interests. As Leila says, there's probably less benefit in targeting new users to write new articles. But I've started over 4000 articles and I bet 90% are WikiProject Queensland. Show me any list of wanted Queensland topics and I'll probably be willing to write about *many * of them (but not all). Similarly if you look at the categories of the articles I write, the category Queensland Heritage Register will come up a lot (probably 1/3 of my articles are about heritage properties). Probably another 1/3 are articles about Queensland towns/suburbs/localities. I think looking at the categories/projects of the articles people write is a very strong indicator of interest areas. And the more articles they write, the more sure you can be that they are confident about starting new articles (a lot of people are not willing to start new articles but will happily contribute to a stub -- probably had a past bad experience with article creation) and the more you can be sure about their areas of interest. With the exception of redirects and disambiguation pages, I would think anyone who has started many articles is likely to have easily-inferred topic space interests. For that matter, a lot of people (myself included) talk about their interest areas on their user page, so key words in user pages that fuzzy-match to project names or category names may be another indicator. However, some of the content gaps on Wikipedia exist because we don't have contributors who are interested in the topic. Given that there is a known difference between the topics that women generally write about compared to men, it's clear that a lack of diversity in editors is likely to lead to content gaps. I would suspect the same is true about other personal characteristics. As an Australian, I am more likely to write about Australian than say Greenland, but I did holiday there last year, so actually I have written a little about Greenland and uploaded some photos, but that's just a "blip" in my contribution profile (and I don't think I started any new articles about Greenland). If we have a content gap about Greenland, maybe we don't have enough Greenlanders to fill it? I think we can't address content gaps unless we also address contributor gaps. This in turn may result in devolving responsibility for things like notability and verifiability down to the Project level. For example, it is often commented that Indigenous Australian topics are a content gap. The problem is a lack of sources. Indigenous Australians did not have a written language so oral sources are very important, but en.Wikipedia isn't keen on oral sources, so there's a content gap that's hard to fill. And I suspect we have very few Indigenous Australians writing for Wikipedia. Statistically 3% of our population self-identifies as Indigenous but they tend to have lower educational attainments which probably makes them less likely to be Wikipedia contributors who, based on the 2011 survey, have above average likelihood of having a university degree. So I think we have two flavours of content gap, those for which we have active contributors in the broader topic space who may be enticed to write about the missing topics (which is the problem being principally addressed by this area of research), and those where we do not have active contributors. Kerry