Figure RNF#3.1 is an example of a coding scheme. It uses questions similar to those in the PILNA numeracy assessment.
The “descriptor” identifies the concept or skill that is being assessed using a particular question. The “sample response” and “code” columns specify the code that is assigned to a particular response.
The sample responses and codes are developed through an iterative process – first the question developers identify what they anticipate student responses will be.
Then content experts evaluate the codes to identify common misconceptions that provide insight into student thinking. These can be thought of as “incorrect answers that a student might give if their logic was not quite right”.
Finally, field trial results are used to validate and refine the coding scheme.
In the example provided, for item 1, the descriptor is that students are expected to round a given number to the nearest ten or hundred.
The three answers students are most likely to give are 300, 290 and 200 and these are assigned a code of 1, 2, and 3 respectively, while all other responses will be assigned code 0. This is when the response of the student does not meet the requirements for answering the question, such as selecting more than one choice in a multiple-choice question. A non-response or a blank will be assigned a code of 9.