Good Evening,

The results of the PISA 2018 test were published at the end of 2019 on the OECD website (https://www.oecd.org/pisa/data/2018database/).

Among the available data are

• the Code book (XLS files): https://www.oecd.org/pisa/data/2018database/PISA2018_CODEBOOK.XLSX
• Cognitive test results (SPSS file): https://webfs.oecd.org/pisa2018/Compendia_Cognitive.zip
• Questionnaire results (SPSS file): https://webfs.oecd.org/pisa2018/Compendia_Questionnaire.zip

I’m questioning about scales computing.

For example, the "Reading proficiency" scale has 5 levels (see https://www.oecd-ilibrary.org/docserver/5f07c754-en.pdf?expires=1582776791&id=id&accname=guest&checksum=891D1B7912818BDF180D8BD3A72368B5#%5B%7B%22num%22%3A1071%2C%22gen%22%3A0%7D%2C%7B%22name%22%3A%22Fit%22%7D%5D, pp. 87-88).

However, in the codebook, I don't see any items related to the "Reading proficiency" scale. Certainly, there are the "CR590Q" items that correspond to a "Reading fluency"... but I don't think that's enough to compute the "Reading proficiency" scale. For example, items identified as "Rapa Nui" also seem to include items about reading.

In short, no matter how hard I look, I can't find information. Do you have any idea where to find the information explaining that item x + item y +... = Reading proficiency Score?

Thank you in advance for your help, best regards,