Warren W. Tryon

Evaluating statistical difference, equivalence, and indeterminacy using inferential confidence intervals: An integrated alternative method of conducting null hypothesis statistical tests

Null hypothesis statistical testing (NHST) has been debated extensively but always successfully defended. The technical merits of NHST are not disputed in this article. The widespread misuse of NHST has created a human factors problem that this article intends to ameliorate. This article describes an integrated, alternative inferential confidence interval approach to testing for statistical difference, equivalence, and indeterminacy that is algebraically equivalent to standard NHST procedures and therefore exacts the same evidential standard. The combined numeric and graphic tests of statistical difference, equivalence, and indeterminacy are designed to avoid common interpretive problems associated with NHST procedures. Multiple comparisons, power, sample size, test reliability, effect size, and cause-effect ratio are discussed. A section on the proper interpretation of confidence intervals is followed by a decision rule summary and caveats.

Fully proportional actigraphy: A new instrument

The relevance of activity measurement is reviewed. Technical information regarding a new, small, lightweight, fully proportional accelerometer-based activity monitor suited for a wide range of wrist, waist, and ankle activity measurements over extended time periods in free-ranging persons is presented. Calibration data demonstrating within- and between-device reliability and validity are presented. Field trial data are presented showing that wrist and waist actigraphs can predict kilocalories of energy expended. The issue of how activity monitors should be validated is discussed. Instrument reliability is distinguished from clinical repeatability. Recommendations are provided to assist investigators with instrument selection.

Validating Internet research: A test of the psychometric equivalence of Internet and in-person samples

This study evaluated the psychometric equivalency of Web-based research. The Sexual Boredom Scale was presented via the World-Wide Web along with five additional scales used to validate it. A subset of 533 participants that matched a previously published sample (Watt & Ewing, 1996) on age, gender, and race was identified. An 8 × 8 correlation matrix from the matched Internet sample was compared via structural equation modeling with a similar 8 × 8 correlation matrix from the previously published study. The Internet and previously published samples were psychometrically equivalent. Co-efficient alpha values calculated on the matched Internet sample yielded reliability coefficients almost identical to those for the previously published sample. Factors such as computer administration and uncontrollable administration settings did not appear to affect the results. Demographic data indicated an overrepresentation of males by about 6% and Caucasians by about 13% relative to the U.S. Census (2000). A total of 2,230 participants were obtained in about 8 months without remuneration. These results suggest that data collection on the Web is (1) reliable, (2) valid, (3) reasonably representative, (4) cost effective, and (5) efficient.

Periodontal Disease as a Function of Life Events Stress

Studies relating stress and oral pathology have been limited to animal experiments or clinical studies of personality and psychological health that have ignored the role of specific life events. The present study related measurements of life events stress to measurements of periodontal disease. Subjects were fifty male volunteers recruited from a pool of dental patients from the Brooklyn VA Outpatient Dental Clinic. Oral examinations were given to determine the degree of periodontitis and gingivitis. Evidence of other somatic symptomatology was assessed by the somatization subscale of the Brief Symptom Inventory. The degree of life events stress was assessed with the Life Experience Survey. Measurements of life events stress were found to be significantly correlated with measures of periodontal disease. Periodontal disease was more severe and widespread as stressors increased. Subjects were found whose general physical health was unrelated to their life situation.

Issues of validity in the diagnostic interview schedule

The Diagnostic Interview Schedule, the chief instrument in contemporary studies in psychiatric epidemiology, enhances the reliability of psychiatric diagnosis and enables lay interviewers to closely reproduce psychiatric interviews. However, despite frequent references in the literature to the validity of the Diagnostic Interview Schedule, most studies fundamentally represent variations of reliability paradigms to the neglect of criterion-related validity. Mistaken assertions of validity persist in the psychometric language used to describe the Diagnostic Interview Schedule. This article examines the basis for claims and counterclaims of validity in accordance with standard psychometric definition, and identifies sources of erroneous reasoning in attempts to infer validity from reliability. The article presents a general framework organizing the process of diagnostic validation and discusses strategies for research seeking to validate psychiatric diagnoses achieved through the Diagnostic Interview Schedule.

Evaluation of mental health. Issues of memory in the diagnostic interview schedule

Research on the Diagnostic Interview Schedule, the chief instrument in contemporary studies in psychiatric epidemiology, has supported its utility in enabling lay interviewers to reproduce psychiatric interviews within an acceptable margin of error. Nonetheless, we propose that the Diagnostic Interview Schedule commits itself to dubious assumptions regarding the accuracy of human memory, shared by other history-taking efforts, by relying on retrospective reports of lifetime DSM-III symptoms and episodic dating of symptom spells. For more than a century, the fallibility of human memory has been the topic of intensive experimental and naturalistic study, a history which is relevant to the construction of instruments like the Diagnostic Interview Schedule. The continuing use of retrospective lifetime symptom reports suggests that this literature has been largely ignored in the development and administration of the Diagnostic Interview Schedule. Prospectively organized research is needed to disclose the limits of human memory for recent psychiatric events and the mediating conditions under which memory for such events can be accurately retrieved and improved.

An Inferential Confidence Interval Method of Establishing Statistical Equivalence that Corrects Tryon's (2001) Reduction Factor.

Evidence of group matching frequently takes the form of a nonsignificant test of statistical difference. Theoretical hypotheses of no difference are also tested in this way. These practices are flawed in that null hypothesis statistical testing provides evidence against the null hypothesis and failing to reject H-sub-0 is not evidence supportive of it. Tests of statistical equivalence are needed. This article corrects the inferential confidence interval (ICI) reduction factor introduced by W. W. Tryon (2001) and uses it to extend his discussion of statistical equivalence. This method is shown to be algebraically equivalent with D. J. Schuirmanns (1987) use of 2 one-sided t tests, a highly regarded and accepted method of testing for statistical equivalence. The ICI method provides an intuitive graphic method for inferring statistical difference as well as equivalence. Trivial difference occurs when a test of difference and a test of equivalence are both passed. Statistical indeterminacy results when both tests are failed. Hybrid confidence intervals are introduced that impose ICI limits on standard confidence intervals. These intervals are recommended as replacements for error bars because they facilitate inferences.

Social Functioning in Predominantly Inattentive and Combined Subtypes of Children With ADHD

Objective: The objective of this study was to compare the social functioning of children with the Combined (CB) and Predominantly Inattentive (PI) subtypes of Attention Deficit/Hyperactivity Disorder (ADHD), controlling for comorbidity and medication-status, which may have confounded the results of previous research. Method: Parents and teachers of rigorously diagnosed unmedicated children with PI or CB subtypes of ADHD, and typical comparison children, rated them on the multidimensional Social Skills Rating Scale (SSRS). Results: After co-varying for oppositionality and anxiety, social impairment was substantial and equivalent in both ADHD groups whether rated by parent or teacher. In addition, when rated by teacher, the nature of the deficits varied by subtype: Children with PI were impaired in assertiveness, whereas children with CB were deficient in self-control. These findings indicate that AD/HD subtypes differ in the nature of their social dysfunction independent of comorbidity and highlight the need for interventions to target their divergent needs.

The effectiveness of biofeedback-assisted relaxation in modifying sickle cell crises.

Eight outpatients with sickle cell disease received six EMG and six thermal half-hour biofeedback training sessions. Statistically significant changes in the desired directions were obtained for the following variables: (a) frontalis muscle tension, (b) digital temperature, (c) frequency of headache as a crisis symptom, (d) frequency of analgesic use, (e) perceived pain intensity, (f) frequency of self-treated crises, and (g) state anxiety. Nonsignificant changes in hospital chart data were found. A 6-month posttreatment follow-up questionnaire revealed the continued effectiveness of the training received regarding headaches and mild pains.

Chronic fatigue syndrome: Assessing symptoms and activity level

Current approaches to the diagnosis and assessment of Chronic Fatigue Syndrome (CFS) rely primarily on scales that measure only the occurrence of various symptoms related to CFS. Such approaches do not provide information on either the severity of symptoms or on fluctuations in symptom severity and activity level that occur over time. As a result, these measures do not reflect the complexities and the interrelations among symptoms. By obscuring the fluctuating nature of CFS and its high variability, current assessment procedures may prevent health care professionals from understanding the complexities of this disease. The present study provides two CFS case studies to illustrate the advantages of using self-reporting rating scales in combination with a device used to measure the frequency and intensity of activity. The implications of this assessment system, which captures the symptom dynamics and variability involved in CFS, are discussed.