Oleg N. Medvedev

Ordinal-To-Interval Scale Conversion Tables and National Items for the New Zealand Version of the WHOQOL-BREF.

The World Health Organisation Quality of Life (WHOQOL) questionnaires are widely used around the world and can claim strong cross-cultural validity due to their development in collaboration with international field centres. To enhance conceptual equivalence of quality of life across cultures, optional national items are often developed for use alongside the core instrument. The present study outlines the development of national items for the New Zealand WHOQOL-BREF. Focus groups with members of the community as well as health experts discussed what constitutes quality of life in their opinion. Based on themes extracted of aspects not contained in the existing WHOQOL instrument, 46 candidate items were generated and subsequently rated for their importance by a random sample of 585 individuals from the general population. Applying importance criteria reduced these items to 24, which were then sent to another large random sample (n = 808) to be rated alongside the existing WHOQOL-BREF. A final set of five items met the criteria for national items. Confirmatory factor analysis identified four national items as belonging to the psychological domain of quality of life, and one item to the social domain. Rasch analysis validated these results and generated ordinal-to-interval conversion algorithms to allow use of parametric statistics for domain scores with and without national items.

Rasch analysis of the Perceived Stress Scale: Transformation from an ordinal to a linear measure:

Rasch analysis was conducted to enhance the precision of the widely used 10-item Perceived Stress Scale using two datasets (n = 450 each) randomly selected from samples of the New Zealand general population (n = 1102), New Zealand university students (n = 479) and US university students (n = 396). The best Rasch model fit (χ2(27) = 29.92, p = .36), good person separation reliability (.80) and coverage (98%) of the sample by the scale items were achieved when locally dependent items were combined into subtests. These findings support reliability and internal structural validity of the 10-item Perceived Stress Scale. The instrument precision can be further improved using the ordinal-to-linear conversion tables published here.

Comparative Effectiveness of Caregiver Training in Mindfulness-Based Positive Behavior Support (MBPBS) and Positive Behavior Support (PBS) in a Randomized Controlled Trial

Caregivers of individuals with intellectual and developmental disabilities are often stressed due to the demands of the job, including the nature and severity of challenging behaviors of the clients, work conditions, degree of management support for the staff, and the demands of implementing some interventions under adverse conditions. Mindfulness-Based Positive Behavior Support (MBPBS) and PBS alone have been shown to be effective in assisting caregivers to better manage the challenging behaviors of clients with intellectual and developmental disabilities. The aim of the present study was to undertake a head-to-head assessment of the effectiveness of MBPBS and PBS alone in a 40-week randomized controlled trial. Of the 123 caregivers who met inclusion criteria, 60 were randomly assigned to MBPBS and 63 to PBS alone, with 59 completing the trial in the MBPBS condition and 57 in the PBS alone condition. Results showed both interventions to be effective, but the caregiver, client, and agency outcomes for MBPBS were uniformly superior to those of PBS alone condition. In addition, the MBPBS training was substantially more cost-effective than the PBS alone training. The present results add to the evidence base for the effectiveness of MBPBS and, if independently replicated, could provide an integrative health care approach in the field of intellectual and developmental disabilities.

Distinguishing transient versus stable aspects of depression in New Zealand Pacific Island children using Generalizability Theory

BACKGROUND The distinction between temporary versus enduring or state/trait aspects of depression is important. More precise distinction would improve understanding of the aetiology of depression and those aspects most amenable to intervention thus identifying more homogeneous, dynamic targets for clinical trials. Generalizability Theory has been proposed as useful for disentangling state and trait components of psychopathology. METHODS We applied Generalizability Theory to determine the relative contributions of temporary and enduring aspects of depression in a widely used screening measure of depression the - 10-item Childrens Depression Inventory (CDI-10; Kovacs, 1985). Participants were children of Pacific Island descent living in New Zealand (n = 668). Data were collected at ages - 9, 11, and 14 years. RESULTS The CDI-10 demonstrated acceptable generalizability across occasions (G = 0.79) with about one third of variance in total scores attributed to temporary and two thirds to more enduring aspects of depression. There were no other significant sources of error variance. Two items were identified as more sensitive than the remaining eight to more dynamic symptoms. LIMITATIONS Studies with briefer test-retest intervals are warranted. Use of this Pacific Island cohort limits generalizability of findings to other cultures and ethnicities. No data were collected on whether participants had received intervention for depression. CONCLUSIONS While the CDI-10 reliably measures both stable and transient aspects of depression in children, the scale does not permit clear distinction between them. We advocate application of Generalizability Theory for developing state/trait depression measures and determining which existing measures are most suitable for capturing modifiable features of depression.

Rasch analysis of the Frost Multidimensional Perfectionism Scale: Rasch analysis of the FMPS

Abstract Objective The Frost Multidimensional Perfectionism Scale (FMPS) is widely used to measure the construct of perfectionism. Previous studies evaluating the factor structure of the FMPS have reported inconsistent findings. The study objective was to examine the psychometric properties of proposed four, five, and six factor solutions of the FMPS using Rasch analysis. Method Using the responses from a sample of New Zealand athletes and exercisers (n = 425) from a variety of sports, we subjected the dataset to Rasch analysis. The overall and individual item fit, unidimensionality, local independence, and person separation reliability were evaluated by treating factors of each model as subtests. Results After disordered thresholds were uniformly rescored, the factor Organisation displayed significant misfit to the model across all three solutions tested. Removal of Organisation and combining two parental facets into one resulted in adequate model fit and good item discrimination ability for all three solutions. The modified six‐factor model was the best in terms of reliability, with no differential item functioning and the highest person separation index. Conclusion The present results support the psychometric properties and internal structural validity of the rescored FMPS with the parental factors combined and without the Organisation facet. Psychometric properties of the instrument can be further enhanced by using the ordinal‐to‐interval conversion table presented here, which does not require modification of the original response format. These findings will be of interest in different areas where accurate assessment of the overall perfectionism trait is important and open new avenues for perfectionism research.

Improving Measurement of Trait Competitiveness: A Rasch Analysis of the Revised Competitiveness Index With Samples From New Zealand and US University Students

Measuring competitiveness is necessary to fully understand variables affecting student learning. The 14-item Revised Competitiveness Index has become a widely used measure to assess trait competitiveness. The current study reports on a Rasch analysis to investigate the psychometric properties of the Revised Competitiveness Index and to improve its precision for international comparisons. Students were recruited from medical studies at a university in New Zealand, undergraduate health sciences courses at another New Zealand university, and a psychology undergraduate class at a university in the United States. Rasch model estimate parameters were affected by local dependency and item misfit. Best fit to the Rasch model (χ2(20) = 15.86, p = .73, person separation index = .95) was obtained for the Enjoyment of Competition subscale after combining locally dependent items into a subtest and discarding the highly misfitting Item 9. The only modifications required to obtain a suitable fit (χ2(25) = 25.81, p = .42, person separation index = .77) for the Contentiousness subscale were a subtest to combine two locally dependent items and splitting this subtest by country to deal with differential item functioning. The results support reliability and internal construct validity of the modified Revised Competitiveness Index. Precision of the measure may be enhanced using the ordinal-to-interval conversion algorithms presented here, allowing the use of parametric statistics without breaking fundamental statistical assumptions.

Exploring constructs of well-being, happiness and quality of life

Background Existing definitions of happiness, subjective well-being, and quality of life suggest conceptual overlap between these constructs. This study explored the relationship between these well-being constructs by applying widely used measures with satisfactory psychometric properties. Materials and Methods University students (n = 180) completed widely used well-being measures including the Oxford Happiness Questionnaire (OHQ), the World Health Organization Quality of Life Questionnaire, the Satisfaction with Life Scale, and the Positive and Negative Affect Scale. We analyzed the data using correlation, regression, and exploratory factor analysis. Results All included well-being measures demonstrated high loadings on the global well-being construct that explains about 80% of the variance in the OHQ, the psychological domain of Quality of Life and subjective well-being. The results show high positive correlations between happiness, psychological and health domains of quality of life, life satisfaction, and positive affect. Social and environmental domains of quality of life were poor predictors of happiness and subjective well-being after controlling for psychological quality of life. Conclusion Together, these data provide support for a global well-being dimension and interchangeable use of terms happiness, subjective well-being, and psychological quality of life with the current sample and measures. Further investigation with larger heterogeneous samples and other well-being measures is warranted.

Rasch analysis and ordinal-to-interval conversion tables for the Depression, Anxiety and Stress Scale:

This study conducted Rasch analysis of the Depression, Anxiety and Stress Scale using responses of 400 participants to produce ordinal-to-interval conversion algorithms not available to date. Minor modifications such as removing the non-fitting item 5 and combining subscales items into super-items were necessary to achieve the best model fit (χ2(15) = 20.28, p = 0.16). The results support internal validity of the modified 20-item Depression, Anxiety and Stress Scale and include ordinal-to-interval conversion tables for use with non-clinical populations that improve reliability and precision of the measure.

The pregnancy-related anxiety scale: A validity examination using Rasch analysis

BACKGROUND Pregnancy-related anxiety is increasingly recognised as a common condition that is associated with many deleterious outcomes for both the mother and infant (e.g., preterm birth, postnatal depression). Limitations in the psychometric properties and/or breadth of existing scales for pregnancy-related anxiety highlight the need for a psychometrically sound measure to facilitate effective screening and possible early interventions. The recently developed Pregnancy-related Anxiety Scale (PrAS) was evaluated using Rasch analysis to explore how the scales psychometric properties could be fine-tuned. METHOD A sample of 497 pregnant women completed the PrAS. Data were subjected to Rasch analysis, and the resulting scale structure examined using Confirmatory Factor Analysis. RESULTS After minor modifications, the Rasch model with 33-items and 8-factors demonstrated good fit, unidimensionality and excellent targeting and internal consistency. Confirmatory Factor Analysis confirmed the final structure, and Cronbachs alpha demonstrated excellent reliability. LIMITATIONS The use of the same sample for all analyses was a potential limitation due to the possibility of sample-specific influences. CONCLUSIONS The Rasch analysis further supports the internal construct validity of the PrAS. Ordinal to interval score conversions provide added precision to the analysis of the PrAS scores. The Rasch results, together with previous validation evidence, point to the PrAS as a comprehensive and psychometrically sound screening scale for pregnancy-related anxiety. The PrAS offers clinicians the ability to screen for pregnancy-related anxiety. The subscales provide additional insights into a womans pregnancy-related anxiety and her specific areas of concern, enabling more targeted interventions.

Distinguishing between enduring and dynamic concussion symptoms: applying Generalisability Theory to the Rivermead Post Concussion Symptoms Questionnaire (RPQ)

Background The Rivermead Post Concussion Symptoms Questionnaire (RPQ) is a widely-used, 16-item measure of concussion symptoms yet its ability to assess change in the symptom experience over time has come under criticism. We applied Generalisability theory to differentiate between dynamic and enduring aspects of post-concussion symptoms and to examine sources of measurement error in the RPQ. Materials and Methods Generalisability theory was applied using the longitudinal design with persons as the object of measurement. Patients with a traumatic brain injury (n = 145; aged ≥16 years) were assessed at three time occasions (1, 6 and 12 months post-injury) using the RPQ. Results The RPQ showed overall strong generalisability of scores (G = .98) across persons and occasions with a minor proportion of variance attributed to the dynamic aspect of symptoms reflected by interaction between person and occasion. Items measuring concentration, fatigue, restlessness and irritability reflected more dynamic patterns compared to more enduring patterns of sensitivity to noise, impatience, nausea and sleep disturbance. Conclusion The RPQ demonstrated strong reliability in assessing enduring post-concussion symptoms but its ability to assess dynamic symptoms is limited. Clinicians should exercise caution in use of the RPQ to track dynamic symptom change over time. Further investigation is necessary to enhance the RPQ’s ability to assess dynamic symptoms and to address measurement error associated with individual items.