A standard error of measurement (SEM) is an estimate of possible error associated with an individual student’s test score.  The SEM can be described as a band of error.  A test score is an estimate of a student’s true test performance; however, when the SEM is applied, it indicates that a reasonable chance exists that the student’s true score may be slightly higher or slightly lower than what is reported.  For the Iowa Test of Basic Skills (ITBS) and Iowa Test of Educational Development (ITED), the SEM’s are presented in ranges, indicating where the student’s true score would like fall (see table below.)