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PSYCHOMETRIC PROPERTIES
The CogniCheck Online Memory Screening tests known collectively as the Computer Reliant Evaluative and Web Screening (CREWS) Tests of Neuropsychological Functioning have been standardized, normed, and scientifically evaluated in samples of individuals between 45 and 86 years of age who resided in the United States. This page provides an overview of the psychometric properties of the CREWS Tests of Neuropsychological Functioning, that includes the results of the normative study, as well as a summary of the reliability and validity of the memory screening measures. Please note that the information provided herewithin is intended primarily for licensed health care professionals and individuals with extensive/advanced training in psychometrics and neuropsychological assessment. While other individuals may find this information enlightening, it is intended to be utilized only for informational purposes and is not to be used to make definitive diagnoses, recommendations, and/or treatment decisions, nor is it intended for use in any litigation cases or proceedings. Furthermore, utilization of this information by persons without adequate psychometric training may result in inaccurate/erroneous interpretations of the data, as well as individuals' memory screening report scores. NORMATIVE STUDY
To determine the "norms" (i.e., means and standard deviations) for each portion of the CREWS Tests of Neuropsychological Functioning and age group, a scientifically rigorous normative study was conducted where CogniCheck Online Memory Screenings were completed by a large sample of cognitively intact individuals, with generally unremarkable medical and psychiatric histories, who resided in geographically diverse regions of the United States. Table 1 below provides the demographic characteristics of the normative sample who ranged in age from 45 to 69 years, while Table 2 contains the demographic characteristics of the normative study participants who were 70 to 86 years of age. Table 2 also includes summary data for the entire normative study sample of 297 participants. Table 1. Demographic Characteristics of the Normative Study Sample: Ages 45 - 69
Table 2. Demographic Characteristics of the Normative Study Sample: Ages 70 - 86
Age-related normative data (i.e., "norms"), cited in terms of the mean and standard deviation for each portion of the CREWS Tests of Neuropsychological Functioning and age group, are provided in Tables 3 and 4 below. Specifically, Table 3 provides the memory screening test norms for persons between 45 and 64 years of age, while Table 4 contains the norms for individuals 65 to 86 years of age. The maximum possible scores for each portion of the CREWS Tests of Neuropsychological Functioning are also included in these tables. Table 3. Age-related Norms (i.e., Means and Standard Deviations) for the CREWS Tests of Neuropsychological Functioning: Ages 45 - 64
Table 4. Age-related Norms (i.e., Means and Standard Deviations) for the CREWS Tests of Neuropsychological Functioning: Ages 65 - 86
DETERMINATION of DESCRIPTIVE CATEGORIES
The distances, in terms of standard deviations (SDs) that particular memory screening raw scores fall from their respective age-related means, are utilized in the determination of raw scores' descriptive categories. Such standard deviations from the age-related means may be calculated via use of the following formula:
For example, the distance (in standard deviations) that a 76-year-old individual's CREWS Test of Facial Memory Delayed Recognition task raw score of 29 falls from the respective age-related mean may be calculated as follows:
Please also note that, for your convenience, all CogniCheck Online Memory Screening reports provide interpretation of the CREWS Tests of Neuropsychological Functioning raw scores in terms of both percentiles (%) and descriptive categories. Table 5. Descriptive Categories and Standard Deviation Ranges
RELIABILITY and INTERCORRELATIONS
The reliability of neuropsychological tests typically refers to the amount/level of consistency, dependability, and stability in the tests' measurements and scores. To examine the reliability/internal consistency of the CREWS Tests of Neuropsychological Functioning, Chronbach's alpha reliability coefficients were calculated for each test portion utilizing the memory screening data obtained from the 297 normative study participants. Evidence of the reliability of the CREWS Tests of Neuropsychological Functioning is found in Table 6, which provides the Chronbach's alpha reliability coefficients for each memory screening test portion when the entire sample of participants was utilized in the analyses. As noted in this table, reliability coefficients range from .64 for portions of the CREWS Test of Facial Memory to a high of .90 for the CREWS Test of Digit Recall Total Score. The intercorrelations between the various portions of the CREWS Tests of Neuropsychological Functioning, that are also cited in Table 6, provide evidence of the validity of the memory screening tests. In particular, the correlations between portions of the CREWS Test of Verbal Learning are notably higher than those between portions of this test and portions of the CREWS Tests of Facial Memory and Digit Recall. Similarly, the correlation between the Immediate and Delayed Recognition portions of the CREWS Test of Facial Memory is greater than the correlations between these test portions and portions of the CREWS Tests of Verbal Learning and Digit Recall. Table 6. Reliability Coefficients and Intercorrelations for the CREWS Tests of Neuropsychological Functioning
VALIDATION STUDY
In addition to the intercorrelations cited in Table 6, the construct validity, and in particular, the convergent and discriminant validity, of the CREWS Tests of Neuropsychological Functioning was examined via a scientifically rigorous "validation" study of 25 individuals who ranged in age from 45 to 74 years (Mean = 57.08, SD = 8.40), with educational levels ranging from 10 to 24 years (Mean = 14.90, SD = 2.87). Among this sample of participants, two reported medical histories of strokes, three indicated histories of transient ischemic attacks (i.e., TIAs), while one person's history was remarkable for meningitis and another individual's history included migraine headaches. Additionally, at the time of this study, four participants acknowledged depressive symptomatology and nine individuals were taking at least one psychotropic medication (e.g., an antidepressant). To evaluate convergent and discriminant validity, study participants were administered (in a counterbalanced order) the CREWS Tests of Neuropsychological Functioning and a series of standardized neuropsychological tests and measures that are commonly utilized by licensed clinical neuropsychologists in clinical practice, including measures of hand grip strength (i.e., Grip Strength task; Reitan & Wolfson, 1993), verbal fluency (i.e., FAS Test; Spreen & Strauss, 1998), visual-organization skills (i.e., Hooper Visual Organization Test; Hooper, 1983), overall cognitive status (i.e., Mini Mental State Examination; Folstein, Folstein & McHugh, 1975), auditory-verbal learning/memory (i.e., Rey Auditory Verbal Learning Test; Rey, 1964), cognitive processing speed and response inhibition (i.e., Stroop Color & Word Test; Stroop, 1935, Golden, 1978), visuo-motor scanning abilities, sequencing skills, and cognitive flexibility (i.e., Trail Making Test, Parts A & B; Reitan, 1979, Reitan & Wolfson, 1993), attention/concentration, rote memory, and aspects of working memory (Wechsler Memory Scale-III, Digit Span subtest; Wechsler, 1997), and visual memory/facial recognition (i.e., Wechsler Memory Scale-III, Faces I & II subtests; Wechsler, 1997). Evidence of the convergent and discriminant validity of the CREWS Tests of Neuropsychological Functioning may be found in Tables 7 and 8 below. Specifically, these tables provide the correlations/validity coefficients between the CREWS Tests of Neuropsychological Functioning and the standardized neuropsychological tests and measures commonly utilized in clinical practice. For example, the generally higher correlations between portions of the CREWS Test of Verbal Learning and portions of another verbal memory test (i.e., Rey Auditory Verbal Learning Test), as compared to the lower correlations between portions of the CREWS Test of Verbal Learning and measurements of hand grip strength (i.e., Grip Strength task) and visual-organization (i.e., Hooper Visual Organization Test) provide evidence of the convergent and discriminant validity, respectively, of the CREWS Test of Verbal Learning. Similarly, examples of the convergent validity of the CREWS Tests of Neuropsychological Functioning are found in the relatively higher correlations between portions of the CREWS Test of Facial Memory and other tests that assess visual memory/facial recognition (i.e., Wechsler Memory Scale-III, Faces I & II), while discriminant validity is demonstrated in the lower correlations between the two portions of the CREWS Test of Facial Memory and measures of cognitive processing speed (i.e., Stroop Color & Word Test) and cognitive flexibility (i.e., Trail Making Test, Part B). Furthermore, the generally higher correlations between the CREWS Test of Digit Recall Total Score and alternate measures of verbal memory (i.e., Rey Auditory Verbal Learning Test, Wechsler Memory Scale-III, Digit Span subtest), as compared to the lower correlations between the CREWS Test of Digit Recall Total Score and measures of visual-organization abilities (i.e., Hooper Visual Organization Test) and cognitive processing speed (i.e., Stroop Color & Word Test) provide examples of the convergent and discriminant validity of the CREWS Test of Digit Recall. It should be noted that numerous other examples of convergent and discriminant validity may be found upon detailed analysis of the correlations between the CREWS Tests of Neuropsychological Functioning and the other commonly utilized neuropsychological tests and measures that are cited in Tables 7 and 8. Table 7. Correlations between the CREWS Tests of Neuropsychological Functioning and other Neuropsychological Tests and Measures
Table 8. Correlations between the CREWS Tests of Neuropsychological Functioning and other Neuropsychological Tests and Measures
Folstein, M. F., Folstein, S. E., & McHugh, P. R. (1975). "Mini-Mental State:" A practical method for grading the cognitive state of patients for the clinician. Journal of Psychiatry Research, 12, 189-198. Golden, J. C. (1978). Stroop Color and Word Test. Stoelting Co., Chicago, IL. Hooper, H. E. (1983). Hooper Visual Organization Test (VOT). Los Angeles: Western Psychological Services. Reitan, R. M. (1979). Manual of Administration of Neuropsychological Test Batteries for Adults and Children. Tucson, AZ: Reitan Neuropsychological Laboratories. Reitan, R. M. & Wolfson, D. (1993). Halstead-Reitan Neuropsychological Test Battery: Theory and Clinical Interpretation (Second Edition). Tucson, AZ: Neuropsychology Press. Rey, A. (1964). L'examen clinique en psychologie. Paris: Presses Universitaires de France. Spreen, O. & Strauss, E. (1998). A Compendium of Neuropsychological Tests: Administration, Norms, and Commentary (Second Edition). New York: Oxford University Press. Stroop, J. R. (1935). Studies of interference in serial verbal reaction. Journal of Experimental Psychology, 18, 643-662. Wechsler, D. (1997). Wechsler Memory Scale - Third Edition. San Antonio, TX: The Psychological Corporation.
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