The TIMSS 2019 Item Equivalence Study: examining mode effects for computer-based assessment and implications for measuring trends

Large-scale Assessments in Education

An IERI – International Educational Research Institute Journal

Table 4 Number of items and sample sizes for analysis

Grade	Total cases	Mathematics		Science
Grade	Total cases	Valid items	Average responses per item	Valid items	Average responses per item
Fourth grade (21 countries)	16,894	77	4199	82	4200
Eighth grade (11 countries)	9164	97	2278	110	2270

Counts reflect resulting sample sizes after deleting problematic data and expected non-invariant items