Words correct per minute: The variance in standardized reading scores accounted for by reading speed

The measure words correct per minute (WC/M) incorporates a measure of accurate aloud word reading and a measure of reading speed. The current article describes two studies designed to parse the variance in global reading scores accounted for by reading speed. In Study I, reading speed accounted for more than 40% of the reading composite score variance in 4th‐, 5th‐, and 10th‐grade students. In Study II, reading speed accounted for more than 30% of the reading/language arts composite score variance of fourth‐ and fifth‐grade students. Across both studies, when reading speed was combined with words read correctly and converted to WC/M the additional variance accounted for was less than 10% with one exception, fourth‐grade students' reading/language arts scores. These findings are consistent with various theories regarding reading speed, provide direction for future researchers, and may assuage those concerned that WC/M is primarily a measure of aloud, accurate word reading (i.e., word calling). © 2010 Wiley Periodicals, Inc.