Final answer:
Prorating the sum of scaled scores can lead to artificial inflation and compromised accuracy because it assumes consistent performance on untested sections of an exam.
Step-by-step explanation:
The problem with prorating the sum of scaled scores is that it can artificially inflate scores and compromise accuracy. Prorating means estimating what a student's score would be based on partial information, and this can lead to scores that don't accurately reflect a student's abilities or knowledge. For example, if only a portion of a test is completed, a prorated score assumes that the student would perform consistently on the missing portions, which may not be true.
Such scores might not truly represent the achievement level of the students, especially if the sections they completed were not representative of the test as a whole. Additionally, prorating doesn't account for the difficulty level of missed questions, which may differ from those that were answered. When tests such as the SAT are critically assessed in terms of their quality and usefulness, problems like this show why relying on prorated scores is controversial.