I have multiple monitors on my mac and for some reason on OSX Mavericks my dock kept jumping from one screen to another. This has been happening for too long so I finally spent some time figuring this out.
Go to the screen that the dock currently is not on. Click the center of the screen then move your mouse directly to the bottom —> Voila your dock has moved to this screen!
Talk about an unnecessary feature that I didn’t ask for.