BEFKI GC-K: A Short Scale for the Measurement of Crystallized Intelligence

Abstract

Crystallized intelligence (gc) is a well-established cognitive ability factor that has been conceptualized as reflecting influences of learning, education, and acculturation. In this article, we describe the development of a short knowledge scale for the measurement of gc in five minutes administration time using declarative knowledge items from the sciences, the humanities, and civics. Based on a large item pool we compiled a 32-item knowledge test that was subsequently presented to a nationally representative sample of 1,134 German adults. In the next step, this data were used to derive a short 12-item knowledge scale. A unidimensional measurement model had satisfactory model fit and showed high reliability of the latent factor. There were no substantial floor or ceiling effects in the adult German population. Similar to the full scale, the short scale correlated highly positively with education (ISCED-97) and socio-economic status (ISEI) and was meaningfully related to self-reported knowledge and the Big Five personality traits. Therefore, the short knowledge scale allows for an efficient and valid measurement of crystallized intelligence in survey research.