Defnyddiodd yr Adolygiad swmp sylweddol o dystiolaeth a data cyfredol. Hefyd, comisiynodd ymchwil newydd, pwrpasol ar rai pynciau pwysig, megis modelau o gymwysterau mewn gwledydd eraill, sgiliau llythrennedd a rhifedd, cymwysterau Lefel Mynediad, materion rhyw o ran asesu a chymwysterau galwedigaethol mewn sectorau penodol.
The Review drew on a large body of existing evidence and data. It also commissioned bespoke research on some key topics, such as qualification models in other countries, literacy and numeracy skills, Entry Level qualifications, gender issues in assessment and vocational qualifications in specific sectors.