Similar to overall frequency counts in non-causal qualitative coding ("which themes are mentioned most often?"), we can count the frequency with which particular factors (causes and effects) are mentioned: which causal factors are mentioned most often?

And we can, with caveats interpret the number of mentions of a particular link in a similar way: which causal connections are mentioned most often — and we can, with similar caveats, interpret the frequency with which a link is mentioned as the strength of the evidence for that link. 

We can simply make a table with the number of times each factor was mentioned or cited overall, and sort it in descending order to see the most important ones. In these tables the outgoing (the factor was mentioned as the influence of something else) and incoming (the factor was mentioned as the consequence of something else).