Naming speed and word familiarity as confounding factors in decoding

The present investigation has three aims: (1) to establish a suitable composite index which combines speed and accuracy in the measurement of decoding skill; (2) to examine whether speed acts as a confounding factor in the measurement of decoding ability; and (3) to see whether familiarity with the word, as indicated by the ability to pronounce it, or lack of it acts as a confounding factor in the assessment of spelling skills. Three studies were conducted to fulfill these aims. In the first study, 33 children from Grade 2 were asked to name a list of 40 letters of the alphabet as quickly and as accurately as possible. A combined index of speed and accuracy was computed from these two sets of data using two formulas, which were based on the ‘z’ score and the mean variance score. A Pearson product‐moment correlation coefficient of 0.94 was obtained between the results of the two formulas indicating that the two formulas yield almost identical results. In the second study, 37 fifth‐graders were administered the word‐attack sub‐test of Woodcock Language Proficiency Battery. When the speed and accuracy composite index, based on the ‘z formula’ was applied to the word‐attack scores, it was found that three children were slow decoders even though their scores were within the normal range. In the third study, 39 children from Grade 3 and 40 children from Grade 5 were asked to read aloud a list of words and then these words were administered as a spelling test. Subsequently, their spelling ability was assessed by computing the number of words they could both read and spell correctly. When familiarity of words was included as a factor in assessing spelling ability, five children in Grade 3 and three children in Grade 5 were found to be misclassified as poor spellers. This indicates that including word‐naming speed and word familiarity (i.e. ability to pronounce) produce different metrics than when they are not. Inclusion of speed and familiarity factors in assessment can be helpful in avoiding false negatives and false positives.