There is a large body of research which disagrees with you...
Oechssler, Jörg; Roider, Andreas; Schmitz, Patrick W. (2009). "Cognitive abilities and behavioral biases". Journal of Economic Behavior & Organization. 72 (1): 147–152. doi:10.1016/j.jebo.2009.04.018. Jump up ^ Orr, D. & Guthrie, C. (2005). "Anchoring, information, expertise, and negotiation: New insights from meta-analysis". Ohio St. J. Disp. Resol., 597, 21. SSRN 900152 Jump up ^ Kristensen, Henrik; Gärling, Tommy (1997). "The Effects of Anchor Points and Reference Points on Negotiation Process and Outcome". Organizational Behavior and Human Decision Processes. 71 (1): 85–94. doi:10.1006/obhd.1997.2713.
(edit as I can't reply to the child comment: Yes, you're right of course. Put it down to a mix of multitasking, iphone browser and university-instilled fear of using Wikipedia as a source)
Why not link to the Wiki article you copied the sources from? https://en.wikipedia.org/wiki/Anchoring
There is no one size fits all to negotiations, there are simply too many. I would be hesitant to even apply some kind of 80/20 rule here. There are many kinds of negotiations and not all follow the same pattern, even if all of them in one person's experience have.
I have succeeded when demanding they present a number and when presenting a number. I think there are other important things in negotiations like how numbers are presented and what else is being exchanged, but I do not have good sources for this last bit outside my own experience.
You can do this if you have a lot of leverage. But if you don't -- and most job seekers don't -- then giving a number first will put you at a disadvantage because it reveals how much you think you are worth and simply gives the other side a starting point from which to bring down the price.
This is absolutely 100% wrong. In price negotiations you will almost always fair better if you force the other party to bring up a number first.