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Fragment of a discussion from Proposal talk:A "be bold" campaign
I think whatever form the actual text/banner takes, it needs to be tested greatly to find the most suitable language. Usability research on potential new editors could test the effectiveness of a particular campaign. One might easily find that users find "Be bold" confusing and are unsure of its meaning. Randomized A/B testing could also be used: serve up a couple of campaigns to different pools of users and compare the "conversion" rates of how many of these users become editors.