Exploratory Factor Analyses of the Intelligence and Development Scales-2: Implications for Theory and Practice

Area of Science:

• Psychometrics
• Educational Psychology
• Cognitive Development

Background:

• The Intelligence and Development Scales-2 (IDS-2) is a tool for assessing cognitive abilities.
• Understanding the factor structure of intelligence and scholastic skills is crucial for accurate assessment and interpretation.

Purpose of the Study:

• To examine the factor structure of the intelligence and scholastic skills domains within the IDS-2.
• To investigate the relationship between intelligence factors and scholastic skills.

Main Methods:

• Exploratory factor analyses were conducted on a large standardization and validation sample (N = 2,030, ages 5-20).
• Schmid-Leiman transformations were used to calculate Omega reliability estimates.

Main Results:

• The proposed seven intelligence group factors were only partly supported, with some factors collapsing into a five-factor structure.
• An additional Reading/Writing factor emerged when scholastic skills subtests were included.
• A strong general factor was identified, accounting for a significant portion of the true score variance.

Conclusions:

• The study did not find a clear data-driven separation between intelligence and scholastic skills within the IDS-2.
• The findings suggest a hierarchical structure with a dominant general factor influencing both domains.
• The utility of factor scores for interpreting IDS-2 results is considered.