A 120 item gc test

This is a 120 item measure of crystallized intelligence (gc), more precisely, declarative knowledge. Based on previous findings concerning the dimensionality of gc (Steger et al., 2019), we sampled items from four broad knowledge areas - humanities, life sciences, natural sciences, and social sciences. Each knowledge area contained three domains with ten items each, resulting in a total of 120 items. Items were selected to have a wide range of difficulty and to broadly and deeply cover the content domain. Items are available in German and English. The development of the inital item pool is detailed in Steger et al. (2019). We used and described the 120 item gc measure in two recent publications (Schroeders et al., 2021; Watrin et al., 2021). The items can be found in the accompanying OSF project.

Gc short tests in German

In addition to the 120-item long scale, we also compiled three, parallel 12 item gc short tests with Ant Colony Optimization (ACO). The three parallel test versions were constructed in such a way that they (a) efficiently capture knowledge across 12 knowledge domains (e.g., chemistry, law, art), (b) follow a unidimensional measurement model, (c) allow reliable and (d) precise measurement of factual knowledge, and (e) are gender fair. We used a heterogeneous sample of 1,607 German adults, aged 18–70 years, to construct the parallel test forms using a cross-validation procedure. In addition, we double-checked the psychometric properties of two scales (A/B) in two large independent replication samples. If measurement precision is essential, we recommend the combined scale with 36 items. The rationale for test construction as well as empirical evidence for reliability and validity can be found in Zimny et al. (2024). The items can be found in the associated OSF project.

General Health Knowledge (GHK-75)

The General Health Knowledge (GHK-75) is an inventory of general health knowledge across the following five domains: (a) anatomy, (b) health-promoting behavior, (c) medical treatment, (d) mental health, and (e) physical illness. A total of 75 items were sampled from a larger pool of health-related knowledge items using Ant Colony Optimization, maximizing reliability and construct coverage simultaneously. Test development and psychometric properties are described in more detail in Steger et al. (2022). In the OSF project, we provide an English and a German version of the GHK-75 which interested researchers are welcome to use for their own studies on health knowledge.