Karen M. Schmidt

Psychometric Properties of the Hypoglycemia Fear Survey-II for Adults With Type 1 Diabetes

OBJECTIVE To perform the first comprehensive psychometric evaluation of the Hypoglycemia Fear Survey-II (HFS-II), a measure of the behavioral and affective dimensions of fear of hypoglycemia, using modern test-theory methods, including item-response theory (IRT). RESEARCH DESIGN AND METHODS Surveys completed in four previous studies by 777 adults with type 1 diabetes were aggregated for analysis, with 289 subjects completing both subscales of the HFS-II and 488 subjects completing only the Worry subscale. The aggregated sample (53.3% female, 44.4% using insulin pumps) had a mean age of 41.9 years, diabetes duration of 23.8 years, HbA1c value of 7.7%, and 1.4 severe hypoglycemic episodes in the past year. Data analysis included exploratory factor analysis using polychoric correlations and IRT. Factors were analyzed for fit, trait-level locations, point-measure correlations, and separation values. RESULTS Internal and test-retest reliability was good, as well as convergent validity, as demonstrated by significant correlations with other measures of psychological distress. Scores were significantly higher in subjects who had experienced severe hypoglycemia in the past year. Factor analyses validated the two subscales of the HFS-II. Item analyses showed that 12 of 15 items on the Behavior subscale, and all of the items on the Worry subscale had good-fit statistics. CONCLUSIONS The HFS-II is a reliable and valid measure of the fear of hypoglycemia in adults with type 1 diabetes, and factor analyses and IRT support the two separate subscales of the survey.

Ethnic Identification Biases Responses to the Padua Inventory for Obsessive-Compulsive Disorder

The authors report differential item functioning (DIF) between Black and White participants completing the 60-item Padua Inventory (PI) for obsessive-compulsive disorder (OCD). The authors use an Internet-generated sample that included 105 Blacks, 67 Hispanics, 582 Whites, and 136 additional participants reporting an OCD diagnosis. Factor analysis replicated prior work indicating the PI consists of four factors: contamination fears, checking behaviors, impaired control over thoughts, and fear of losing control over impulses. On the contamination subscale, nonclinical Black and Hispanic mean scores were as high as the OCD group. Comparing Blacks to Whites, the authors applied an item response theory, DIF-graded response model to each factor and found significant DIF on eight items, with biased items in each factor. Results suggest that extraneous factors contribute to racial differences on scores. Cultural practices and fear of being negatively stereotyped may contribute to item bias.

Examining the Behaviour subscale of the Hypoglycaemia Fear Survey: an international study.

The Hypoglycemia Fear Survey (HFS)‐II Behaviour and Worry subscales were developed to measure behaviours and anxiety related to hypoglycaemia in diabetes. However, previous studies found lower reliability in the HFS Behaviour subscale and inconsistent relationships with glucose control. The purpose of this study was to conduct extensive analyses of the internal structure of the HFS Behaviour subscales internal structure and its relationships with diabetes outcomes, including HbA1c and episodes of severe hypoglycaemia.

Item Response Theory and Measuring Abilities

This chapter covers ability measurement in its two dominant traditions: Classical Test Theory and Item Response Theory. CTT methods are based largely on large sampling norms, fixed-length tests, and ordinal-level measurement scales. A persons ability performance is based upon relative standing among a population of individuals for a given test. However, a persons performance, or its change, relative to particular item performance, is not well incorporated. IRT methods use model-based measurement, in which person performance may be referenced to specific item parameters, as well as to relative standing in a population of persons. The meaningfulness of the item parameters is independent of the population of persons sampled. Persons can receive different tests, of varying lengths, and still be meaningfully compared. The scale of measurement for IRT is interval-level, so relative score levels and their change are weighted accordingly. This chapter discusses methodological assumptions, item difficulty, score meaning, test construction, and test evaluation using classical and item response theory approaches. Simple and complex models are presented, and each methods strengths and weaknesses are discussed. Keywords: ability measurement; cognitive ability; individual differences; item response theory; psychometrics; test construction; test scores

Recalled Social Experiences and Current Psychological Adjustment among Adults Reared by Gay and Lesbian Parents

Children of gay and lesbian parents are a diverse group, but existing studies offer limited information about individual differences in their social experiences and subsequent psychological outcomes. In this study, 91 adults reared by gay and lesbian parents responded to measures of recalled social experiences as well as current depressive symptoms, positive and negative affect, and life satisfaction. Participants reported differing social experiences (e.g., stigma) as a function of their sex, family type, gay/lesbian parents sex, and age at which they learned that a parent was gay or lesbian. Despite such diverse experiences, participants reported no significant differences in long-term psychological adjustment. It could be the case that children of gay and lesbian parents learn to cope with difficult social experiences, leading to positive adjustment overall. Indeed, the current sample perceived their social experiences as becoming significantly more positive over the life course, with less stigma and more benefits related to their family situation during adulthood than during earlier developmental periods. Future studies of adaptive coping processes and longitudinal changes in social experiences among offspring of gay and lesbian parents are warranted.

16 Item Response Theory and Measuring Abilities

Ability measurement changed greatly at the end of the last century. Classical test theory (CTT) methods guided measurement for most of the last century. CTT methods are based on large sampling norms, fixed length tests, and ordinal level measurement scales. Here, a persons ability performance is based on relative standing among a population of individuals for a given test. However, a persons performance, or its change, relative to a persons performance on a particular item is not well incorporated. Ability measurement and test theory have evolved into newer methods. These newer approaches, known as item response theory (IRT) methods, are replacing CTT techniques. In IRT methods, person performance may be referenced to specific item parameters, as well as to relative standing in a population of persons. Persons can receive different tests measuring the same unidimensional trait, of varying lengths, and still be meaningfully compared, given that the tests are linked or equated. The scale of measurement for IRT is interval-level, so relative score levels and their change are weighted accordingly. In this chapter, both classical and item response theory approaches will be covered, and each methods strengths and weaknesses discussed. Keywords: ability measurement; classical test theory; item response theory; test theory

An empirically derived short form of the Hypoglycaemia Fear Survey II.

To develop an empirically derived short version of the Hypoglycaemia Fear Survey II that still accurately measures fear of hypoglycaemia.

Predicting and Reducing Driving Mishaps Among Drivers With Type 1 Diabetes

OBJECTIVE Two aims of this study were to develop and validate A) a metric to identify drivers with type 1 diabetes at high risk of future driving mishaps and B) an online intervention to reduce mishaps among high-risk drivers. RESEARCH DESIGN AND METHODS To achieve aim A, in study 1, 371 drivers with type 1 diabetes from three U.S. regions completed a series of established questionnaires about diabetes and driving. They recorded their driving mishaps over the next 12 months. Questionnaire items that uniquely discriminated drivers who did and did not have subsequent driving mishaps were assembled into the Risk Assessment of Diabetic Drivers (RADD) scale. In study 2, 1,737 drivers with type 1 diabetes from all 50 states completed the RADD online. Among these, 118 low-risk (LR) and 372 high-risk (HR) drivers qualified for and consented to participate in a 2-month treatment period followed by 12 monthly recordings of driving mishaps. To address aim B, HR participants were randomized to receive either routine care (RC) or the online intervention “DiabetesDriving.com” (DD.com). Half of the DD.com participants received a motivational interview (MI) at the beginning and end of the treatment period to boost participation and efficacy. All of the LR participants were assigned to RC. In both studies, the primary outcome variable was driving mishaps. RESULTS Related to aim A, in study 1, the RADD demonstrated 61% sensitivity and 75% specificity. Participants in the upper third of the RADD distribution (HR), compared with those in the lower third (LR), reported 3.03 vs. 0.87 mishaps/driver/year, respectively (P < 0.001). In study 2, HR and LR participants receiving RC reported 4.3 and 1.6 mishaps/driver/year, respectively (P < 0.001). Related to aim B, in study 2, MIs did not enhance participation or efficacy, so the DD.com and DD.com + MI groups were combined. DD.com participants reported fewer hypoglycemia-related driving mishaps than HR participants receiving RC (P = 0.01), but more than LR participants receiving RC, reducing the difference between the HR and LR participants receiving RC by 63%. HR drivers differed from LR drivers at baseline across a variety of hypoglycemia and driving parameters. CONCLUSIONS The RADD identified higher-risk drivers, and identification seemed relatively stable across time, samples, and procedures. This 11-item questionnaire could inform patients at higher risk, and their clinicians, that they should take preventive steps to reduce driving mishaps, which was accomplished in aim B using DD.com.

Merging Psychophysical and Psychometric Theory to Estimate Global Visual State Measures from Forced-Choices

Visual acuity, a forced-choice psychophysical measure of visual spatial resolution, is the sine qua non of clinical visual impairment testing in ophthalmology and optometry patients with visual system disorders ranging from refractive error to retinal, optic nerve, or central visual system pathology. Visual acuity measures are standardized against a norm, but it is well known that visual acuity depends on a variety of stimulus parameters, including contrast and exposure duration. This paper asks if it is possible to estimate a single global visual state measure from visual acuity measures as a function of stimulus parameters that can represent the patients overall visual health state with a single variable. Psychophysical theory (at the sensory level) and psychometric theory (at the decision level) are merged to identify the conditions that must be satisfied to derive a global visual state measure from parameterised visual acuity measures. A global visual state measurement model is developed and tested with forced-choice visual acuity measures from 116 subjects with no visual impairments and 560 subjects with uncorrected refractive error. The results are in agreement with the expectations of the model.

Cloninger's Temperament and Character Inventory Correlates with Personality Characteristics of Organ Donation Advocates

Temperament and Character Inventory (TCI) and background questionnaire data were collected from a sample of men and women organ donation advocates (N = 362) as part of a national study to investigate their personality characteristics, temperaments, and attitudes about organ donation advocacy. Goals included identifying unique traits for advocates, and response consistency between the TCI and questionnaire. The TCI results included high scores on Cooperativeness and Self-Directedness, and low on Harm Avoidance dimensions. The questionnaire results indicated that most advocates were White, married, college-educated females, who typically spent less than 2 hr with potential donor families, were satisfied with life and job, and believed they would be in a donation position 2 years from the time surveyed. TCI and questionnaire measures were correlated for Self-Transcendence and Spirituality, Helpfulness and Job Satisfaction, and Compassion and Identification variables.