ABSTRACT
Assessment outcomes may be confounded with nuisance variables that are unrelated to the construct being measured. These variables, sometimes referred to as extraneous variables or contaminants, come from many different sources. The variability of assessment outcomes owing to these variables is often referred to as construct-irrelevant variance (CIV). Constructirrelevant sources of variance threaten the validity of assessment, particularly when they impact the performance of subgroups differently. Among the most influential sources of CIV is the impact of unnecessary linguistic complexity of test items on student assessment outcome.
