Negatively-Worded Multiple Choice Questions: An Avoidable Threat to Validity.

Despite the majority of MCQ writing guides discouraging the use of negatively-worded multiple choice questions (NWQs), they continue to be regularly used both in locally produced examinations and commercially available questions. There are several reasons why the use of NWQs may prove resistant to sound pedagogical advice. Nevertheless, systematic inspection of item-level analysis often reveals anomalous behavior of NWQs on high-stakes examinations, due to otherwise high-performing students selecting the incorrect option for those questions. Highlighting the negative term as commonly recommended does not prevent this, since both anecdotal and empirical evidence suggests that many students answer the question as if it were positively phrased. The continued use of NWQs in high-stakes examinations poses a significant threat to the validity of interpretation based on these assessments. This is a form of "construct-irrelevant variance" within the control of the item writer, and is therefore completely avoidable.