This blog endeavors to share and offer insightful experiments in the realm of psychological and educational measurement. It is tailored for scholars, university researchers, psychologists, educators, teachers, students, and other individuals with an ardent interest in the fields concerning cognitive abilities and assessments.
Wednesday, January 27, 2010
Gender and Education: Their Interplay in Cognitive Test Outcomes at Cogn-IQ.org
Monday, January 25, 2010
Evaluating the Reliability of the Jouve Cerebrals Test of Induction: A Psychometric Analysis
Saturday, January 23, 2010
Revising the Epreuve de Performance Cognitive: Psychometric Properties of the Revised Nonverbal, Sequential Reasoning Test
This study aimed to revise the Epreuve de Performance Cognitive (EPC), a nonverbal, sequential reasoning test, by incorporating a stopping requirement after five consecutive misses, and to evaluate the psychometric properties of the revised EPC. Data from 1,764 test takers were analyzed using various statistical methods. The revised EPC demonstrated high reliability, with a reliability coefficient of .94 and a Cronbach's alpha of .92. Multidimensional scaling analysis confirmed the existence of a continuum of item difficulty, and factor analysis revealed a strong relationship between the revised EPC and Scholastic Assessment Test (SAT) scores, supporting construct validity. The revised EPC also showed high correlations with other cognitive measures, indicating convergent validity. Despite some limitations, the revised EPC exhibits robust psychometric properties, making it a useful tool for assessing problem-solving ability in average and gifted adults. Future research should address study limitations and investigate the impact of timed versus liberally timed conditions on test performance.
Keywords: Epreuve de Performance Cognitive, revised EPC, nonverbal reasoning, sequential reasoning, psychometric properties, reliability, validity.
Introduction
Psychometrics is a vital field within psychological research, focusing on the theory and techniques involved in psychological measurement, particularly the design, interpretation, and validation of psychological tests. The study of the psychometric properties of tests is crucial for ensuring their reliability, validity, and accuracy in assessing the intended psychological constructs. The present study aims to revise the Epreuve de Performance Cognitive (EPC), a nonverbal, sequential reasoning test, and investigate its psychometric properties.
Sequential reasoning tests are designed to assess an individual's ability to understand and predict patterns, sequences, and relationships (DeShon, Chan, & Weissbein, 1995). These tests have been widely used in different contexts, including assessing cognitive abilities, aptitude, and intelligence (Carroll, 1993). The original EPC has been employed in various research contexts, including studies on problem-solving, and giftedness (Jouve, 2005). However, the test's stopping criterion has been a topic of debate, with some researchers arguing that it may limit the test's effectiveness in distinguishing between high and low performers.
The present study aims to address this concern by adding a stopping requirement after five consecutive misses to the EPC, thereby revising the test. The rationale behind this revision is to minimize potential fatigue and frustration associated with attempting numerous difficult items without success. To assess the psychometric properties of the revised EPC, the study employs various statistical techniques, including the Spearman-Brown corrected Split-Half formula (Brown, 1910; Spearman, 1910), Cronbach's alpha (Cronbach, 1951), multidimensional scaling analysis, principal components factor analysis, and correlation analysis (Nunnally & Bernstein, 1994).
The reliability and validity of the revised EPC are of utmost importance for its potential applications in research and practice. Previous studies have utilized the EPC as a measure of cognitive abilities, such as problem-solving and time for taking the test (Jouve, 2005). Moreover, the EPC has been used in studies with gifted individuals, highlighting its potential to identify high-performing individuals (Jouve, 2005). The study's primary objective is to assess the reliability and validity of the revised EPC and compare its psychometric properties to well-established tests, such as Raven's Advanced Progressive Matrices (Raven et al., 1998), Cattell's Culture-Fair Intelligence Test-3A (Cattell & Cattell, 1973), and the Scholastic Assessment Test (SAT) (College Board, 2010).
This study seeks to address the potential limitations of the original EPC by revising the test and adding a stopping requirement after five consecutive misses. The main goal is to investigate the psychometric properties of the revised EPC, focusing on its reliability, validity, and relationship with other established cognitive measures. By providing a comprehensive analysis of the revised EPC's psychometric properties, this study aims to contribute to the literature on sequential reasoning tests and their potential applications in research and practice.
Method
Research Design
The current study utilized a quasi-experimental design to revise the Epreuve de Performance Cognitive (EPC), a nonverbal, sequential reasoning test, and to evaluate its psychometric properties (Blair & Raver, 2012). Specifically, a stopping requirement was added, where the test would be terminated after five consecutive misses, and the resulting test scores were compared to other established cognitive measures.
Participants
A total of 1,764 participants, who completed the revised EPC, were included in this study. No exclusion criteria were set.
Materials
The revised EPC was employed as the primary measure for this study. The original EPC is a nonverbal, sequential reasoning test that assesses problem-solving ability (Jouve, 2005). Modifications to the original EPC included the addition of a stopping requirement after five consecutive misses. The revised EPC was then compared to other well-established cognitive measures, such as Raven's Advanced Progressive Matrices (APM; Raven, 1998), Cattell's Culture-Fair Intelligence Test-3A (CFIT; Cattell & Cattell, 1973), and the Wechsler Adult Intelligence Scale (WAIS; Wechsler, 1997), to establish convergent validity.
Procedures
Upon obtaining informed consent, participants were administered the revised EPC individually. The revised EPC is computerized and consisted of 35 items, with participants instructed to complete as many items as possible under liberally timed conditions. To ensure data quality, the stopping requirement was implemented, terminating the test after five consecutive misses. For the convergent validity studies, participants were then asked to complete the APM, CFIT, or WAIS. When possible, participants were asked to report their previous scores, especially on college admission tests, such as the SAT.
Statistical Analyses
The data were analyzed using various statistical techniques, such as the Spearman-Brown corrected Split-Half formula, Cronbach's alpha, multidimensional scaling analysis, principal components factor analysis, and correlation analysis. The Spearman-Brown formula and Cronbach's alpha were used to assess the reliability of the revised EPC scores, while multidimensional scaling analysis was employed to examine the test's structure with ALSCAL (Young et al., 1978). Principal components factor analysis was conducted to establish construct validity, and correlation analysis was used to determine the convergent validity of the revised EPC with other cognitive measures. Apart from MDS, all the analyses were carried out with Excel.
Results
Statistical Analyses
The goal of this study was to revise the Epreuve de Performance Cognitive (EPC), a nonverbal, sequential reasoning test, by adding a stopping requirement after five consecutive misses, and to examine the psychometric properties of the revised EPC. The data collected from 1,764 test takers were analyzed using various statistical tests, including the Spearman-Brown corrected Split-Half formula, Cronbach's alpha, multidimensional scaling analysis, principal components factor analysis, and correlation analysis.
Reliability of the Revised EPC
The reliability of the scores yielded by the revised EPC was assessed using the Spearman-Brown corrected Split-Half formula and Cronbach's alpha. The entire sample of 1,764 test takers yielded a reliability coefficient of .94, calculated using the Spearman-Brown formula, indicating a high level of internal consistency. Additionally, Cronbach's alpha was found to be .92, further supporting the reliability of the revised EPC.
Multidimensional Scaling Analysis
A multidimensional scaling analysis was conducted to confirm the existence of a continuum in items from the easiest to the hardest. The two-dimensional solution appeared in a typical horseshoe shape, as shown in Figure 1, with a Stress value of .14 and an RSQ of .92. These results suggest that the revised EPC has a coherent structure in terms of item difficulty.
Figure 1. Two-dimensional scaling for the Items of the Revised EPC.
Note. N = 1,764. Root Squared Mean (RSQ) = .92. Kruskal's Stress = .14.
Factor Analysis
A principal components factor analysis was performed using the data of 95 participants who reported recentered Scholastic Assessment Test (SAT) scores. The first unrotated factor loading for the revised EPC was .83. The Math reasoning scale of the SAT loaded at .82, and the Verbal reasoning part at .75. This indicates that the EPC shares considerable variance with the SAT, supporting its construct validity.
Correlations with Other Measures
The revised EPC raw scores were found to have high correlations with other cognitive measures. A correlation of .82 was observed between the EPC raw scores and the Raven's Advanced Progressive Matrices (APM) in a sample of 134 subjects, while a correlation of .81 was found between the EPC raw scores and the Cattell's Culture-Fair Intelligence Test-3A (CFIT) in a sample of 156 observations. Additionally, a correlation of .85 was found between the EPC raw scores and the Full Scale IQ (FSIQ) on the Wechsler Adult Intelligence Scale (WAIS) in a highly selective sample of 23 adults with an average FSIQ of 131.70 (SD=24.35). These results demonstrate the convergent validity of the revised EPC.
Limitations
Despite the promising results, some limitations should be considered. First, the sample size of certain sub-analyses (e.g., the correlation with FSIQ on the WAIS) was relatively small, which may limit the generalizability of the findings. Second, the study did not explore potential differences between timed and liberally timed conditions, which could provide further insight into the performance of the revised EPC.
The revised EPC, with the addition of a stopping requirement after five consecutive misses, demonstrated strong psychometric properties, including high reliability and convergent validity. The multidimensional scaling analysis confirmed the existence of a continuum in items from the easiest to the hardest, and the factor analysis demonstrated the construct validity of the revised EPC in relation to the SAT. These results support the utility of the revised EPC for assessing problem-solving ability in individuals of average ability level and gifted adults. Further research should address the limitations of the current study and explore the potential impact of timed versus liberally timed conditions on the revised EPC performance.
Discussion
Interpretation of Study Results and Relation to Previous Research
The main objective of this study was to revise the Epreuve de Performance Cognitive (EPC; Jouve, 2005) by implementing a stopping requirement after five consecutive misses and to evaluate its psychometric properties. The results indicate that the revised EPC possesses high reliability, as demonstrated by a Spearman-Brown corrected Split-Half formula coefficient of .94 and a Cronbach's alpha of .92. These findings align with previous research emphasizing the importance of test reliability in psychological assessments (Nunnally, 1978).
The multidimensional scaling analysis revealed a coherent structure in terms of item difficulty, confirming the existence of a continuum from the easiest to the hardest items. This result is consistent with prior studies that have employed multidimensional scaling analysis to identify the underlying structure of cognitive test items (Thiébaut, 2000). Furthermore, the factor analysis indicated that the revised EPC shares substantial variance with the SAT (College Board, 2010), thus supporting its construct validity. These findings are in line with previous research establishing the validity of cognitive tests in measuring problem-solving abilities (Carroll, 1993).
Implications for Theory, Practice, and Future Research
The strong psychometric properties of the revised EPC, including its high reliability and convergent validity, have significant implications for both theory and practice. The revised EPC can serve as a useful tool for assessing problem-solving ability in individuals of average ability level and gifted adults, potentially informing educational and occupational decision-making processes (Lubinski & Benbow, 2006). Moreover, the positive relationship between the revised EPC and established cognitive measures, such as the SAT, Raven's APM, CFIT, and WAIS, further substantiates the relevance of nonverbal, sequential reasoning tests in cognitive assessment (Sternberg, 2003).
Given the current findings, future research could explore the impact of time constraints on EPC performance, as the present study did not investigate potential differences between timed and liberally timed conditions. Additionally, researchers could examine the applicability of the revised EPC in diverse populations and settings, such as in clinical or cross-cultural contexts (Van de Vijver & Tanzer, 2004).
Limitations and Alternative Explanations
Despite the promising results, this study has some limitations that may affect the generalizability of the findings. First, the sample size for certain sub-analyses (e.g., the correlation with FSIQ on the WAIS) was relatively small, potentially limiting the robustness of these results (Cohen, 1988). Second, the study did not investigate the potential impact of timed versus liberally timed conditions on the revised EPC performance, which could provide valuable insights into the test's utility in various contexts (Ackerman & Kanfer, 2009).
Future Directions
The revised EPC, with the addition of a stopping requirement after five consecutive misses, demonstrated strong psychometric properties, including high reliability and convergent validity. The findings support the utility of the revised EPC in assessing problem-solving ability in individuals of average ability level and gifted adults. Future research should address the limitations of the current study, explore the potential impact of timed versus liberally timed conditions on the revised EPC performance, and investigate its applicability in diverse populations and settings (Sackett & Wilk, 1994).
Carroll, J. B. (1993). Human cognitive abilities: A survey of factor-analytic studies. New York: Cambridge University Press. https://doi.org/10.1017/CBO9780511571312
Spearman, C. (1910). Correlation calculated from faulty data. British Journal of Psychology, 3(3), 271-295. https://doi.org/10.1111/j.2044-8295.1910.tb00206.x
Analyzing the Item Structure of the General Knowledge Subtest in the Jouve-Cerebrals Crystallized Educational Scale (JCCES) Using Multidimensional Scaling
Abstract
The purpose of this study was to analyze the item structure of the General Knowledge Subtest in the Jouve-Cerebrals Crystallized Educational Scale (JCCES) using multidimensional scaling (MDS) analyses. The JCCES was developed as a more efficient assessment of cognitive abilities by implementing a stopping rule based on consecutive errors. The MDS analyses revealed a horseshoe-shaped scaling of items in the General Knowledge Subtest, indicating a continuum wherein the constraints for dissimilarities have all been supported. The two-dimensional scaling solution for the General Knowledge Subtest indicates that the items are well-aligned with the construct being assessed. Limitations of the study, including the sample size and assumptions made in the MDS analyses, are discussed.
Keywords: Jouve-Cerebrals Crystallized Educational Scale, General Knowledge Subtest, multidimensional scaling, stopping rule, cognitive abilities, item structure
Introduction
Psychometric tests have been used for decades to assess cognitive abilities in various domains (Bors & Stokes, 1998; Deary, 2000). However, lengthy tests have been associated with several issues, including fatigue, boredom, and inaccuracy in results (Sundre & Kitsantas, 2004). To address these issues, the Cerebrals Cognitive Ability Tests (CCAT) were revised, resulting in the development of the Jouve-Cerebrals Crystallized Educational Scale (JCCES). One modification made to the JCCES was implementing a stopping rule after a certain number of consecutive errors, a technique used in some Wechsler subtests and the Reynolds Intellectual Assessment Scale (RIAS) (Wechsler, 2008; Reynolds & Kamphaus, 2003). The purpose of this study was to analyze the item structure of the General Knowledge Subtest in the JCCES, specifically examining the two-dimensional scaling solution using multidimensional scaling (MDS) analyses.
Method
The use of Rasch analysis to estimate item difficulty parameters is a well-established technique in psychometrics (Wright & Stone, 1979). Similarly, the adoption of a stopping criterion based on consecutive errors is a technique used in other cognitive ability tests, such as the Wechsler Adult Intelligence Scale (WAIS) and the Kaufman Assessment Battery for Children (KABC) (Wechsler, 2008; Kaufman & Kaufman, 1983). The present study administered the JCCES General Knowledge Subtest to 588 participants and implemented a stopping criterion of five consecutive errors after determining that three consecutive errors were inappropriate. The rearrangement of items based on Rasch estimates allowed for the examination of the item structure in a more systematic and objective manner. MDS analyses were then conducted to explore the underlying structure of the item response data.
Results
As shown in Figure 1, the present study's MDS analyses produced a two-dimensional scaling solution for the General Knowledge Subtest with a Kruskal's Stress of .18 and a squared correlation (RSQ) of .87. The horseshoe-shaped scaling pattern of the items indicates a continuum of difficulty levels, with the constraints for dissimilarities supported. It is called Guttman's effect (Guttman, 1950; Collins & Cliff, 1990). This pattern is consistent with the concept of item difficulty in psychometric testing (Lord & Novick, 1968) and supports the validity of the test in measuring cognitive abilities. These findings also suggest that the implementation of a stopping rule based on consecutive errors is an effective way to improve the efficiency of the cognitive ability test.
Figure 1. Multidimensional Scaling (MDS) of the General Knowledge subtest items.
Discussion
The results of this study show the benefits of implementing a stopping rule to improve the efficiency of cognitive ability tests. The horseshoe-shaped scaling pattern observed in the General Knowledge Subtest aligns well with the concept of item difficulty in psychometric testing. However, the limitations of this study should be acknowledged. The sample size of 588 is relatively small for this type of analysis, and caution should be taken when generalizing the findings to other populations (Hair et al., 1998). Additionally, the selection of the stopping criterion at five consecutive errors was determined based on the current sample and may not be optimal for all populations. Methodological limitations, such as the assumptions of linearity and homoscedasticity in the MDS analyses, may have influenced the results.
Conclusion
In conclusion, the JCCES provides a more efficient assessment of cognitive abilities, with the General Knowledge Subtest demonstrating a horseshoe-shaped scaling pattern indicative of a continuum of difficulty levels. The two-dimensional scaling solution indicates that the items are well-aligned with the construct being assessed. Although there are limitations to the study, these findings provide valuable insights into the item structure of the JCCES General Knowledge Subtest and support the use of a stopping rule based on consecutive errors to improve the efficiency of the test. Future research could explore the generalizability of the findings to larger and more diverse samples, as well as investigate the optimal stopping criterion for different populations.
References
Bors, D. A., & Stokes, T. L. (1998). Raven's Advanced Progressive Matrices: Norms for first-year university students and the development of a short form. Educational and Psychological Measurement, 58(3), 382–398. https://doi.org/10.1177/0013164498058003002
Collins, L. M., & Cliff, N. (1990). Using the longitudinal Guttman simplex as a basis for measuring growth. Psychological Bulletin, 108(1), 128–134. https://doi.org/10.1037/0033-2909.108.1.128
Deary, I. J. (2000). Looking down on human intelligence: From psychometrics to the brain. Oxford, UK: Oxford University Press. https://doi.org/10.1093/acprof:oso/9780198524175.001.0001
Guttman, L. (1950). The basis for scalogram analysis. In S. A. Stouffer, L. Guttman, E. A. Suchman, P. F. Lazarsfield, S. A. Star, & J. A. Clausen (Eds.), Measurement and prediction (pp. 60 – 90). Princeton, NJ: Princeton University Press.
Hair, J. F., Anderson, R. E., Tatham, R. L., & Black, W. C. (1998). Multivariate data analysis (Vol. 5). Upper Saddle River, NJ: Prentice Hall.
Kaufman, A. S., & Kaufman, N. L. (1983). Kaufman Assessment Battery for Children. Circle Pines, MN: American Guidance Service.
Lord, F. M., & Novick, M. R. (1968). Statistical theories of mental test scores. Reading, MA: Addison-Wesley.
Reynolds, C. R., & Kamphaus, R. W. (2003). Reynolds Intellectual Assessment Scales (RIAS) and the Reynolds Intellectual Screening Test (RIST), Professional Manual. Lutz, FL: Psychological Assessment Resources.
Sundre, D. L., & Kitsantas, A. (2004). An exploration of the psychology of the examinee: Can examinee self-regulation and test-taking motivation predict consequential and non-consequential test performance? Contemporary Educational Psychology, 29(1), 6–26. https://doi.org/10.1016/S0361-476X(02)00063-2
Wechsler, D. (2008). Wechsler Adult Intelligence Scale–Fourth Edition (WAIS–IV). San Antonio, TX: Pearson. https://doi.org/10.1037/t15169-000
Wright, B. D., & Stone, M. H. (1979). Best test design: Rasch measurement. Chicago, IL: MESA Press.
Saturday, January 9, 2010
Evaluating the Reliability and Validity of the TRI52: A Computerized Nonverbal Intelligence Test
Friday, January 8, 2010
Assessing the Validity and Reliability of the Crystallized Cognitive Assessment Test (CCAT)
Abstract
The Cerebrals Cognitive Ability Test (CCAT) is a psychometric test battery comprising three subtests: Verbal Analogies (VA), Mathematical Problems (MP), and General Knowledge (GK). The CCAT is designed to assess general crystallized intelligence and scholastic ability in adolescents and adults. This study aimed to investigate the reliability, criterion-related validity, and norm establishment of the CCAT. The results indicated excellent reliability, strong correlations with established measures, and suitable age-referenced norms. The findings support the use of the CCAT as a valid and reliable measure of crystallized intelligence and scholastic ability.
Keywords: Cerebrals Cognitive Ability Test, CCAT, psychometrics, reliability, validity, norms
Introduction
Crystallized intelligence is a crucial aspect of cognitive functioning, encompassing acquired knowledge and skills that result from lifelong learning and experiences (Carroll, 1993; Cattell, 1971). The assessment of crystallized intelligence is vital for understanding an individual's cognitive abilities and predicting their performance in various academic and professional settings. The Cerebrals Cognitive Ability Test (CCAT) is a psychometric test battery designed to assess general crystallized intelligence and scholastic ability, divided into three distinct subtests: Verbal Analogies (VA), Mathematical Problems (MP), and General Knowledge (GK).
As a psychometric instrument, the CCAT should demonstrate high levels of reliability, validity, and well-established norms to be considered a trustworthy measure. The current study aimed to evaluate the CCAT's psychometric properties by examining its reliability, criterion-related validity, and the process of norm establishment. Furthermore, the study sought to establish the utility of the CCAT for predicting cognitive functioning in adolescents and adults.
Method
Participants and Procedure
A sample of 584 participants, aged 12-75 years, was recruited to evaluate the reliability and validity of the CCAT. The sample was diverse in terms of age, gender, and educational background. Participants were administered the CCAT alongside established measures, including the Reynolds Intellectual Assessment Scales (RIAS; Reynolds & Kamphaus, 2003), Scholastic Assessment Test - Recentered (SAT I; College Board, 2010), and the Wechsler Adult Intelligence Scale III (WAIS-III; Wechsler, 1997). The data collected were used to calculate reliability coefficients, correlations with other measures, and age-referenced norms.
Reliability Analysis
The reliability of the full CCAT and its subtests was assessed using the Spearman-Brown corrected Split-Half coefficient, a widely-accepted measure of internal consistency in psychometric tests (Cronbach, 1951). This analysis aimed to establish the CCAT's measurement error, stability, and interpretability.
Validity Analysis
Criterion-related validity was assessed by examining the correlations between the CCAT indexes and established measures, including the RIAS Verbal Index, SAT I, and WAIS-III Full-Scale IQ and Verbal IQ. High correlations would indicate the CCAT's validity as a measure of crystallized intelligence and scholastic ability.
Norm Establishment
Norms for the CCAT were established using a subsample of 160 participants. The CCAT scales were compared with the RIAS VIX and WAIS-III FSIQ and VIQ to develop age-referenced norms. The RIAS VIX changes over time were applied to adjust the CCAT indexes, ensuring up-to-date and relevant norms.
Results
Reliability
The full CCAT demonstrated excellent reliability, with a Spearman-Brown corrected Split-Half coefficient of .97. This result indicates low measurement error (2.77 for the full-scale index) and good measurement stability. The Verbal Ability scale, derived from the combination of VA and GK subtests, also displayed a high level of reliability, with a coefficient of .96, supporting its interpretation as an individual measure.
Validity
The criterion-related validity of the CCAT was confirmed through strong correlations with established measures. The full CCAT and Verbal Ability scale demonstrated high correlations with the RIAS Verbal Index (.89), indicating a strong relationship between these measures. Additionally, the CCAT was closely related to the SAT I (.87) and both the WAIS-III Full-Scale IQ (.92) and Verbal IQ (.89), further supporting the CCAT's validity as a measure of crystallized intelligence and scholastic ability.
Discussion
The findings of this study provide strong evidence for the reliability and validity of the CCAT as a psychometric tool for assessing general crystallized intelligence and scholastic ability. The high-reliability coefficients indicate that the CCAT yields consistent and stable results, while the strong correlations with established measures support its criterion-related validity.
Moreover, the established age-referenced norms allow for accurate interpretation of CCAT scores across various age groups, making it suitable for adolescents and adults up to 75 years old. The computerized version of the CCAT provides raw scores for each subtest, further facilitating the assessment process and interpretation of results.
Despite these strengths, it is important to acknowledge the limitations of the current study. The sample was limited in size and diversity, which may affect the generalizability of the findings. Future research should aim to replicate these results in larger and more diverse samples, as well as explore the predictive validity of the CCAT in real-world academic and professional settings.
Conclusion
The Cerebrals Cognitive Ability Test (CCAT) is a reliable and valid psychometric instrument for measuring general crystallized intelligence and scholastic ability in adolescents and adults. The study findings support the use of the CCAT in educational and psychological assessment contexts and contribute to the growing body of literature on psychometric test development and evaluation.
References
Carroll, J. B. (1993). Human cognitive abilities: A survey of factor-analytic studies. New York: Cambridge University Press. https://doi.org/10.1017/CBO9780511571312
Cattell, R. B. (1971). Abilities: Their structure, growth, and action. Houghton Mifflin.
College Board (2010). Scholastic Assessement Test. Retrieved from https://www.collegeboard.org/
Cronbach, L. J. (1951). Coefficient alpha and the internal structure of tests. Psychometrika, 16(3), 297-334. https://doi.org/10.1007/BF02310555
Reynolds, C. R., & Kamphaus, R. W. (2003). Reynolds Intellectual Assessment Scales (RIAS) and the Reynolds Intellectual Screening Test (RIST), Professional Manual. Lutz, FL: Psychological Assessment Resources.
Wechsler, D. (1997). Wechsler Adult Intelligence Scale - Third Edition. San Antonio, TX: Psychological Corporation.