Regarding the Jesus Seminar, N.T. Wright writes in Jesus and the Victory of God:
Great reliance has been placed on the work of John Kloppenborg, who has painstakingly analysed the Q material into its supposed three stages of composition.
This is prima facie perplexing to me. How do scholars like Kloppenborg purport to work out stages of composition of a document without any manuscripts? (Not a rhetorical question.)