Decomposing the Variance in Reading Comprehension to Reveal the Unique and Common Effects of Language and Decoding

Area of Science:

• Psychology
• Education
• Linguistics

Background:

• The Simple View of Reading posits reading comprehension as a product of decoding and language abilities.
• Debate exists on whether the sum or product of components better predicts reading comprehension.
• No prior research has partitioned variance to assess shared and unique contributions of decoding and language.

Purpose of the Study:

• To decompose the variance in reading comprehension explained by decoding and language.
• To examine the unique and shared variance explained by decoding and language across different grade levels.
• To inform an expanded Simple View of Reading model.

Main Methods:

• A regression approach was used to partition variance.
• Data from students in grades 1, 6, and 10 were analyzed.
• Measures included receptive vocabulary (language), timed word reading (decoding), and a standardized reading comprehension test.

Main Results:

• In grade 1, common variance between decoding and language significantly explained reading comprehension.
• By grade 10, unique language effects and common effects of language and decoding predominantly explained reading comprehension.
• The relative importance of unique and shared variance shifted with grade level.

Conclusions:

• The Simple View of Reading can be expanded to account for unique and shared variance.
• Understanding the interplay between decoding and language is vital for reading development.
• Educational interventions may benefit from targeting both unique and shared components of reading skills.