I am using the PISA dataset of 2012 to calculate the variance explained by ESCS (socio-economic status).

**I followed the steps in the PISA DATA ANALYSES Manuel 2nd edition for SAS:**

*1. SAS® syntax for preparing a data file for the multilevel analysis (Box 16.3 at p.238-239).*

*2. SAS® syntax for running multilevel models with the PROC_MIXED_PV macro (Box 16.6 at p.242).*

*3. Calculating the results:*

I used following equation:

1-(T2/T1)

T2 = is the intercept/between-school variance in model 2 and;

T1 = is the intercept/between-school variance in the empty model

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First I tried using SPSS, than SAS, but either way I am not getting the same results as in the examples given by PISA.

For example: According to PISA, in Norway, 7% of variance in math performance is explained by ESCS. According to my calculations that is wrong, as much as 20% is explained by ESCS, and 25% by ESCS and MU_ESCS.

Interestingly when I run a one-way ANOVA, than the R-square is (almost) the same percentages as in the examples by PISA.

I only have a few more days left before submitting my BA Paper, and I really need to calculate the variance for countries that are not included in the examples on PISA's website.

Can someone please please help me figure out why I am not getting the right percentage.