In situations like this where you want people to click your header link to actually navigate somewhere, I've found that it's best not to have drop down navigation sub menus, and if you do, don't make the header link navigational.
But you wanted facts. Instead of trying to find someone else's study, let's just do our own. Let's take a look at what some would consider the top 2 companies in the world: Apple and Microsoft:
Apple does not have drop down navigation sub menus. Their header links are navigational and take you to the home page of that particular area.
Initially, Microsoft does not have drop down navigation sub menus either. They require you to click on the header links and that activates the drop down navigation sub menu. That said, the header links themselves are not navigational links.
You can pick either style: navigational header links with no drop down navigation sub menus or non-navigational header links that, when clicked, activate the navigation sub menus. If you notice though, both styles require a click on the header link, navigational or not. This way, there's no way your user can miss it.