The diagnosis of learning disorders in children with German as a second
language (L2) represents a challenge for psychological diagnostics. One
goal of the DiLeDaZ project in the LONDI research network (Learning
Disorders - Online Platform for Diagnostics and Intervention;
coordination: M. Hasselhorn & G. Schulte-Körne) is to review established
reading, spelling and math tests with regard to their test fairness for
L2 learners. One possible way to rule out discrimination against a
subgroup (here: L2 learners) is to investigate measurement invariance
(MI). In order to be able to compare latent mean values between
different groups, here L1 vs. L2, the presence of MI is a prerequisite.
So far, school achievement tests in Germany have not been tested
sufficiently with regard to their invariance for children with German as
their mother tongue (L1) and German second-language learners (L2). On
the basis of available data sets, measurement invariance of some
established reading, spelling and math tests was investigated by
step-by-step procedures in two-group comparisons. The investigation
revealed that all measurement models fit well with the data. A stepwise
restriction of the models does not lead to a significant decrease in the
model fit, so that the same assumptions hold for both groups regarding
factor structure, loadings, item-specific difficulties and
reliabilities. The assumption of a strict measurement invariance is
justified for all tests examined here. Since the latent traits are thus
measured identically in both groups, differences in test performance can
be clearly attributed to existing differences in ability. Thus, the
assessment of school achievement and a diagnosis of learning disorders
based on these achievement tests are fair for L2 learners. However, the
question now arises as to whether the same structural relationships
between school achievement and known predictors can be demonstrated for
children with L2 vs. L1, and whether weak reading, spelling or math
performance in L2 learners can be attributed to the same underlying
deficits as in children with German as their mother tongue.
