Determining strength of evidence is confused by conclusions of judges and jurors (12)

'determining strength' is the definition.

'evidence is confused by conclusions of judges and jurors' is the wordplay.
'confused' indicates an anagram.
'by' says to put letters next to each other.
'conclusions of' suggests the final letters.
'and' is a charade indicator (letters next to each other).
'jurors' becomes 's' (I can't explain this - if you can you should believe this answer much more).
The final letter of 'judges' is 's'.
'evidence'+'is'='evidenceis'
'evidenceis' with letters rearranged gives 'decisivene'.
'decisivene'+'s'+'s'='DECISIVENESS'

'of' is the link.