GCSE Economics: In the mark schemes, what is the difference between AO1a, AO1b and AO3a, AO3b? OCR Customer Support 26 November 2019 16:59 Updated AO1a refers to knowledge and AO1b to understanding AO3a refers to analysis and AO3b refers to evaluation. Referring them to a and b comes from the Ofqual guidance on the assessment objectives. Return to qualification page Related articles GCSE Economics: With regards to exam questions - is the highest mark question 6 marks? GCSE Economics: Are students required to calculate elasticities? Comments 0 comments Article is closed for comments.