grade-8-science-content-pdf

Relative Achievement in Science Content Domains

Exhibit 2.2.13 shows countries’ average achievement in each of the four content science domains relative to their overall average achievement (presented from highest to lowest overall average achievement). The exhibit also highlights differences based on a test of statistical significance between the average domain score and the overall science score using an alpha level of 0.01. A smaller alpha level was used to flag statistical significance of subdomain differences to reduce the number of false positives that can be expected due to multiple comparisons across multiple countries and dependent sub-scores. Differences are computed for each student and averaged across the country, rather than comparing different groups of students as in previous exhibits in this section. This within-student dependency leads to considerably smaller standard errors (given in parentheses and reported together with the estimates in the exhibit).