The Effects of Synthetic Phonics Teaching on Reading and Spelling Attainment: A Seven-Year Longitudinal Study (Clackmannanshire)
Johnston, R. S., & Watson, J. E. · 2005
grade Dquasi-experimentdeveloper-involvedfailed
Sample
~300 children
Population
Scotland (Clackmannanshire), general primary pupils P1-P7 (ages 5-11).
Design
Non-random assignment; synthetic-phonics group received extra literacy time/attention and differed demographically; no baseline matching; word-reading measured against chronological age, not a matched control. Later-years data reported online only, not peer-reviewed.
Key findings
The study that drove England's synthetic-phonics-first mandate (Rose Review 2006) - and a cautionary tale in evidence grading. The famous +3y6m word-reading advantage sits beside a +3.5-MONTH comprehension advantage (a ~12x gap), and the design is confounded (extra instruction time, non-random, unmatched). Policy influence vastly exceeded evidential warrant (Ellis 2007; Wyse & Goswami 2008).
Genetic confound
High: non-random groups differ on unobserved ability/demographics; the word-reading-vs-chronological-age comparison has no counterfactual.
Replication notes
Never replicated at this magnitude; RCT-only meta (Torgerson 2006) finds no synthetic-vs-analytic difference, contradicting its framing.
Effects
| Outcome | Metric | Value | Measure | Timing | Vs | Horizon | Class |
|---|---|---|---|---|---|---|---|
| Word reading, end of P7 | reading-age advantage | +3 years 6 months (vs chronological age) | mixed | end-of-treatment | none | end-of-treatment | domain-skill |
| Spelling, end of P7 | spelling-age advantage | +1 year 8 months | mixed | end-of-treatment | none | end-of-treatment | domain-skill |
| Reading comprehension, end of P7 | comprehension-age advantage | +3.5 MONTHS only | standardized | end-of-treatment | none | end-of-treatment | domain-skill |
Cited by
- Systematic/explicit phonics vs whole language and balanced literacystrong supportconf: highgc: low