See the most recent review of all existing research:
www.educationuncovered.co.uk/news/131686/little-evidence-in-favour-of-systematic-synthetic-phonics-research-review-concludes-.thtml
“There is little evidence” in favour of any one approach to the teaching of phonics over another, a major new research study has concluded, in what looks like a direct challenge to recent government policy.
A team of academics from the universities of Durham and Sheffield carried out a “tertiary” review of studies of the teaching of reading. This was a synthesis of all existing research on the subject, with the team evaluating the findings of 12 “systematic reviews” of existing research, which themselves embraced 452 individual studies in total.
The exercise provided what the researchers, Carole Torgerson, Greg Brooks, Louise Gascoine and Steve Higgins, describe as the “most up-to-date overview of the results and quality of the research on phonics,” across a number of countries.