The method of assessment used by the IBO is criterion-referenced and not norm-referenced. That is to say that candidates are judged by their performance in relation to the identified assessment criteria and not in relation to the rest of the population being assessed.

The score to the left is the IBO score (in red), the score to the right is a conversion to the numerical grade a student will receive in my classroom (in blue).  It is assumed that all essays demonstrate proper English standards (i.e. proper grammar, spelling and punctuation).
 

mark band 19-20                                                                                                                                                 99-100 It is not expected that an essay in this mark band would be a “perfect” answer but it should be directly focused and show a depth of historical understanding. There is likely to be evidence of wide reading. In addition, the candidates answer will demonstrate one of the following: a highly developed awareness of historiographical issues, a high level of conceptual ability, or a successful challenge to the assumptions implied in the question

mark band 17-18                                                                                                                                                  97-98 The specific question is answered in a direct and focused manner. There is likely to be evidence of reading which has been effectively used in the answer. There may be an appreciation of historiographical issues. Arguments and concepts will be well developed.

mark band 14-16                                                                                                                                                 94-95-96 The question is effectively and relevantly addressed and the answer is supported by accurate knowledge. The answer demonstrates a consistent level of analytical ability, although not all aspects of the issues have necessarily been addressed.

mark band 11-13                                                                                                                                                 91-92-93 The knowledge shown is generally accurate, relevant and adequate to support a sound answer. The candidate's analysis is not fully developed

mark band 8-10                                                                                                                                                   83-86-89 The answer is mainly descriptive or in narrative form and has some explicit or implicit relevance, or is made relevant by its conclusion. Alternatively, there is a coherent argument based on barely sufficient material.

mark band 6-7                                                                                                                                                    77-80 The question is only partially addressed and there is a limited demonstration of appropriate skills. There is a limited degree of accurate and relevant knowledge.

mark band 4-5                                                                                                                                                    71-74 The knowledge shown is limited, often inaccurate and of marginal relevance to the question. The question is not addressed effectively and there is very little evidence of appropriate skills.

mark band 1-3                                                                                                                                                   62-65-68 There is very little relevant knowledge and little or no understanding of the question. The candidate's answer is no more than a collection of isolated facts or generalizations bearing little relation to each other or the question. There is no evidence of appropriate skills.

mark band 0                                                                                                                                                      59 If a candidate does not achieve the standard described by mark band 1-3 then 0 should be recorded.