The problem is researchers aren't going to want/be able to spend the time to properly document negative/unsurprising results. The financial incentives in place don't support it despite its incredible value.
Sometimes it is just the count the number of published papers, or that dividing by the number of authors, or some weight if you are the first or the last author.
Number of citations, h-index, ...
About the journal, there is the impact factor and many somewhat arbitrary ranks...
A paper in a totally obscure journal that is not cited by other papers, has the same weight than a blog post.
