Sum Scale Research Articles

Correcting the illogicality in probability data of mutually exclusive behaviours

One application of the Verbal Probability Scale (VPS) that has immense value to marketers is its use in estimating market shares and customer preferences of mutually exclusive offerings. The literature on this application reveals illogicality in the data produced with the scale. Researchers have corrected the illogicality by employing a weighting technique. This technique enables the logical interpretation of data, albeit with certain ramification on the estimates. The current study investigated the extent to which the ramification affected the estimates. Comparisons were made between the weighted means produced on VPS with the means produced on a Constant Sum Scale (CSS), a scale that controls for illogical assignment of scores. The results showed that the weighted means were comparable to that produced on CSS for a set of mutually exclusive mobile phone payment plans. The paper discusses the implications of the results and future research needed for developing this particular application.

Lowering missing item values in quality-of-life questionnaires: an interventional study

Missing item values (MIV) often occur in quality-of-life (QoL) questionnaires. This study aimed to examine whether the use of introductory exemplary questions reduces the number of MIV and what patient-related factors influence effectiveness of such a QoL form training. In a randomized controlled study in ten primary care practice settings, a total of 215 consecutively recruited patients with at least one chronic disease were requested to complete the Medical Outcomes Study 36 Items Short Form (SF-36) questionnaire, German version 1.0. Prior to filling out the QoL form, a sample of randomly selected patients answered three simple written questions similar in wording and appearance to the original SF-36 questionnaire. In total, 126 (58.6%) patients completed the SF-36 questionnaire without MIV. Despite MIV the forms of 46 (21.4%) patients were still computable, i.e., scoring of scales was possible after use of the standardized SF-36 imputation algorithm. After the imputation procedure, MIV significantly hampered generating computable sum scales in 29 (26.6%) of the control group and 14 (13.2%) of the interventional group (P<0.05). A univariate analysis suggested no evidence that the number of MIV was reduced by the intervention. However, intervention led to a significant decrease of MIV in males but not in females. The education status affected the number of missing data independent of intervention. This cross-sectional study showed that the prior use of three self-created questions similar in wording and appearance to the SF-36 questionnaire significantly reduces MIV in male patients. School qualification of QoL respondents inversely correlated with the number of questionnaire MIV, but independent of education status all subjects did benefit from the QoL form training.

Sexuality and subjective wellbeing in male patients with congenital heart disease

Objective:To assess physical and psychological concerns related to sexuality, the prevalence of erectile dysfunction and their relationship to patients’ quality of life.Design:Questionnaire-based survey.Setting:Tertiary care centre.Patients:Consecutive sample of 332 men with...

Election Forecasting: Development of the Constant Sum Scale to be Used in Telephone Surveys

Election Forecasting: Development of the Constant Sum Scale to be Used in Telephone Surveys

Election Forecasting: Development of the Constant Sum Scale to be used in Telephone Surveys

The Constant Sum Scale has been successfully tested to forecast election results in face-to-face surveys. As political polls are carried out using telephone surveys, there was a need to test the scale for use in telephone surveys. In this study the Constant Sum Scale was tested for implementation in a telephone survey. The study was carried out during an election that used the single transferable voting system, and the Constant Sum Scale was utilised to forecast the election outcome. The validation against the election results showed that the Constant Sum Scale was successful in ranking the candidates in the order they prevailed in the final electoral result. Respondents’ understanding, based on the judgements given by interviewers, was at a satisfactory level. The overall results suggest that the Constant Sum Scale can be implemented effectively in telephone surveys and is recommended for telephone polling of voters.

The Transition to University

Freshmen students at six Canadian universities completed questionnaires that assessed the quality of match between their individual needs and their university environment. The Student-University Match Questionnaire (SUM), a theoretically derived scale, was developed and demonstrated excellent psychometric properties (Cronbach's alpha = .87). Furthermore, interviews were conducted with students who had deregistered from their universities and a matched control group of students who remained enrolled. The interviews provided construct and predictive validity for the SUM scale. They also revealed important themes of student-environment match concerns for these emerging adults, confirming the characteristics of development, exploration, and mobility as identified by Arnett. Implications are discussed.

Psychological consequences of life‐saving cardiac surgery in patients and partners: measurement of emotional stress by the Impact of Event Scale

AbstractThe objective of this study is to investigate the long‐term psychological aftermaths of the implantation of a ventricular assist device as bridge to successful heart transplantation. Cross‐sectional, retrospective assessment of 30 patients (aged 48.1 ± 11.5 years, m/f = 28/2, 64.8 ± 32.2 months, range 12–134 months after transplantation) and 21 partners (m/f = 1/20) by standardized instruments [Impact of Event Scale (IES‐R), Hospital Anxiety and Depression Scale] and a questionnaire about specific problems regarding the time on the device (Artificial Heart Questionnaire) at Vienna Transplant Center (Austria) were used. Twenty patients suffered from dilatative cardiomyopathy and 10 of ischemic cardiomyopathy. The assist remained implanted for 158 ± 130 days (range 28–711). After transplantation, patients had to stay in Coronary care unit for 8.5 ± 7.3 days (range1–40) and remained in hospital for 29.8 ± 7.9 days (range 21–51) before they were transferred to a rehabilitation unit. None of the patients but 23 per cent of the partners (n = 6) met the criteria for post‐traumatic stress disorder (Maercker cut‐off &gt; 0). Thereby, the IES‐R sum scales differed significantly between the two groups [21.2 ± 15.1 (mean ± standard deviation) for patients versus 38.1 ± 27.8 for partners, respectively, p = 0.001]. Two per cent of the patients and 19 per cent (p = 0.055) of the partners showed mild to moderate depression, and 4 per cent of patients and 23 per cent (p = 0.007) of their partners reported mild to moderate anxiety. None of the results were significantly influenced by the time elapsed since transplantation, the patients' age, diagnoses or indication for heart transplantation. However, the type of assist device had significant effects on hyperarousal (p = 0.040), avoidance (p = 0.030), sum scale (p = 0.050) and IES‐R‐cut‐offs (p = 0.039) of the spouses. Concerning the specific heart support related questions, patients rated all the items lower than did their respective spouses. These values significantly were lower for pain (p = 0.034) and stroke (p = 0.008) in spouses than patients. Despite of patients being much closer to a life threat, it is their partners who experience significantly more psychological distress even in the long run. Our findings highlight the need to support the supporting persons. Copyright © 2008 John Wiley &amp; Sons, Ltd.

A comparison of importance weights and willingness-to-pay measures derived from choice-based conjoint, constant sum scales and best–worst scaling

We review the measurement of product attribute importance, and find little consensus in definition or measurement methods. We compare four measurement methods: 1) two direct methods whereby respondents report the importance of attributes using best–worst scaling or constant sum scales, and 2) two indirect methods derived from discrete choice experiments. Our comparisons rely on previous findings that choice experiments are externally valid to use as the standard. We find high agreement within direct or indirect methods, but less agreement between direct and indirect methods. Our results also demonstrate that inferences derived from indirect measures appear to be susceptible to context effects related to the particular attributes a researcher chooses to investigate. We discuss implications for current and future research.

An analysis of buying center decisions through the salesforce

In this paper we examine whether classical customer surveys that are used to predict group buying decisions can be replaced by the method of interviewing the salesforce. We set up a two-step research approach. In the first step, we examined the predictive performance of different measurement processes in a salesforce survey (self-explicated approach and limit conjoint analysis for the preferences and constant sum scale and for the influence measurement limit conjoint analysis). In the second step, we conducted a classical customer survey using limit conjoint analysis and compared it with the predictions derived from the salesforce survey. Our results show that when surveying the salesforce (1) limit conjoint analysis is superior to the self-explicated approach in measuring preferences. With regard to the measurement of influence, we did not find any significant differences between the two procedures. (2) Our major findings are that the predictions derived from the salesforce survey are not only more practical because of the relatively low costs but that they also outperform those from the customer survey.

Therapieumstellung auf Aripiprazol im Schweizer Praxisalltag (TRACE: TReatment with Aripiprazole based on Case Experience)

Background: The lack of compliance of many patients suffering from schizophrenia, usually a result of the strong side effects of their medication, motivates both physicians and patients to search for other effective antipsychotic therapies. Although several second-generation antipsychotic drugs are currently available, relatively few studies exist in Switzerland that consider the expectations of patients upon changing their therapy, apart from the efficacy and tolerability of the medication. Objective: The aim of the present survey TRACE (Treatment with Aripiprazole based on Case Experience) was to scientifically monitor the effects of a switch from the patient's current therapy to Aripiprazole, a new antipsychotic drug, and to gain more information about everyday practices in the Swiss medical system. Methods: This 12-week open-label prospective survey was carried out between June 2004 and February 2005 in Switzerland, in cooperation with 112 psychiatrists. The investigation comprised of 303 patients with schizophrenia and schizo-affective disorders in 89% (n = 270) of the cases and other psychiatric disorders in 11% (n = 33). After having added Aripiprazole to their current therapy, the downtitration of their current neuroleptic drug took place during the follow-up of this survey. Approximately 80% of the patients received a dose of 15 mg/day Aripiprazole and the remaining 20% between 10 and 30 mg/day. During the first visit (V1) both the physicians and the patients filled out a questionnaire with the following items: diagnosis, pretreatment, BPRS Extended, BMI, therapy goal and quality of life (SF-12), this information being collected on a non-standardised interview. During a second, not obligatory visit (V2), after 4 to 8 weeks, and during the final visit (V3), after 12 weeks, the following data were recorded during a non-standardised interview: efficacy, BPRS-Extended, tolerability, BMI, quality of life (SF-12) and reasons for possible therapy withdrawals. Results: From the initial group of 303 patients, 78.2% (n = 238) were observed over the entire follow-up period of 12 weeks and 21.8% (n = 66) withdrew from it. During the first visit, 80.5% (n = 244) of the patients recorded that they expected an improved tolerability with the new antipsychotic after therapy change. From these patients most expectations (59.7%, n = 181) focused on a lower body weight. Others reasons for a switch were expectations for: fewer negative symptoms (45.5%) and fewer positive symptoms (40.3%). The average overall BPRS-Extended score was reduced significantly (p 30) was reduced from 26.9% (n = 78) at the beginning of the investigation to 24.1% (n = 70). The overall BMI could also be lowered significantly (mean A = -0.5, p <0.001). In 79.9% (n = 242) of the patients no suspected adverse reactions arose. 20.1% (n = 61) registered side effects including restlessness, sleeping disorders or nausea. The value of the ShortForm SF-12 for the determination of the quality of life showed that there was a significant improvement in both the physical and the psychological sum scale (mean A = +3.3 and A = +7.9, p <0.001, respectively). Conclusion: The results of this investigation show that the switch to Aripiprazole provides a clear improvement for many patients with schizophrenia or schizo-affective disorders included in this survey with regard to efficacy and tolerability. Expectations and hopes of Swiss patients, and their physicians, from a change in therapy were fulfilled, in most cases, by the end of the observation period.

Mini-Mental Status Examination: Mixed Rasch model item analysis derived two different cognitive dimensions of the MMSE

Objectives This study published in two companion papers assesses properties of the Mini-Mental State Examination (MMSE) with the purpose of improving the efficiencies of the methods of screening for cognitive impairment and dementia. Study Design and Setting An item analysis by conventional and mixed Rasch models was used to explore empirically derived cognitive dimensions of the MMSE, to assess item bias, and to construct diagnostic cut-points. The scores of 1,189 elderly residents were analyzed. Results Two dimensions of cognitive function, which are statistically and conceptually different from those obtained in previous studies, were derived. The corresponding sum scales were (1) age-correlated MMSE scale (A-MMSE scale: orientation to time, attention/calculation, naming, repetition, and three-stage command) and (2) non–age-correlated MMSE scale (B-MMSE scale: orientation to place, registration, recall, reading, and copying). The “writing” item was not included due to differential effects of age and sex. The analysis also showed that the study sample consisted of two cognitively different groups of elderly. Conclusions The findings indicate that a two-scale solution is a stable and statistically supported framework for interpreting data obtained by means of the MMSE. Supplementary analyses are presented in the companion paper to explore the performance of this item response theory calibration as a screening test for dementia.

The Impact of Promotions on the Convergence in Preference Elicitation Methods

Three methods frequently used in research to assess product preferences were compared to determine their degree of convergence. These methods included: (1) constant sum scale, a subjective probability measure, (2) conjoint measurement, and (3) actual choice. These methods were analyzed along context, i.e., non-promotion versus promotion. Subjects were 43 university personnel. Subjects utilized each of the measures to rate their preferences for 9 soft drink brands. Methods were found to exhibit a strong degree of convergence for large market share brands. This may suggest that the elicitation methods may be measuring similar constructs when preferences are high and market share is high. However, when preferences are low and market share is low, contexts effects (i.e., promotions) may reduce the amount of convergence in preference elicitation methods.

Metformin treatment of polycystic ovary syndrome improves health-related quality-of-life, emotional distress and sexuality

In polycystic ovary syndrome (PCOS), changes in physical appearance, menstrual disturbances and infertility result in psychological distress and reduced quality-of-life. Metformin improves biochemical, clinical and reproductive parameters in PCOS women. In a prospective, observational study, we analysed the effects of metformin treatment on health-related quality-of-life (HRQL), emotional well-being and sexuality in PCOS. No placebo-treated control group was included. Before, during and after 6 months of treatment, changes in clinical and endocrine parameters, quality-of-life, psychological disturbances and sexuality were assessed in 64 PCOS patients using validated questionnaires (SF-36, SCL-90-R) and visual analogue scales. Patients were also compared with published normative data for the validated questionnaires. During treatment, HRQL, particularly the psychosocial aspects (indicated by significant increases in SF-36 scales Vitality, Social Function, Emotional Role Function, Mental Health, Psychological Sum scale) and emotional well-being (reflected by significant lowering of SCL-90-R scales) improved. These improvements in HRQL were significantly correlated with a reduction in body weight and significantly more pronounced in patients with normalized menstrual cycles. In addition, PCOS women were significantly more satisfied with their sex life and reported higher frequencies of sexual intercourse following treatment. Treatment can improve the psychosocial, emotional and psychosexual situation of PCOS patients. Although at least some of these effects may be related to the reduction of individual clinical symptoms (i.e. weight loss, normalization of menstrual disturbances, improvement of acne), this observational study does not allow us to clearly discern the role of symptom constellation and does not preclude non-specific and/or placebo effects. Nevertheless, emotional distress and reduced quality-of-life are clearly not an inevitable consequence of PCOS and should be considered as adjunct treatment goals in future studies.

Posttraumatic stress disorder after implantation of a Mechanical Assist Device Followed by Heart Transplantation: Evaluation of Patients and Partners

Aim We sought to investigate the prevalence of posttraumatic stress disorder, anxiety, and depression in patients and their partners after implantation of a mechanical assist device as a bridge to heart transplantation. Methods This was a retrospective assessment of 41 patients (age 46.3 ± 12.0 years; male-female ratio, 38:3; time since transplantation, 55.3 ± 34.2 months [range, 7–122 months) and 27 partners (male-female ratio 2:25) by standardized instruments (Impact of Event Scale, Hospital Anxiety and Depression Scale), in 2 University Heart Transplant Centers (Vienna, Austria, Munster, Germany). The duration of the support systems (MicroMed DeBakey-VAD in 17 patients, Novacor in 10, Thoratec in 8, TCI HeartMate in 5, and Berlin Heart Incor in 1 patient) ranged from 28 to 711 (176 ± 146) days. Results None of the patients, but 23% of the partners (n = 6), met the criteria for posttraumatic stress disorder (Maercker cutoff >0). The Impact of Event Scale (IES) sum scales differed significantly between the 2 groups (21.2 ± 15.1, mean ± SD) for the patients versus 38.1 ± 27.8 for the partners, respectively; P = .001). Two percent of the patients, but 19% of the partners, showed mild to moderate depression; 4% of patients, but 23% of their partners, reported mild to moderate anxiety. None of the results were significantly influenced by the time since transplantation, patient age, diagnoses, type of assist device, or indication for heart transplantation. Conclusions Despite patients being much closer to a life threat, their partners experience significantly more psychologic distress even in the long run. Our findings highlight the need for attention to the supporting persons.

Recurrence plot statistics and the effect of embedding

Recurrence plots provide a graphical representation of the recurrent patterns in a timeseries, the quantification of which is a relatively new field. Here we derive analytical expressions which relate the values of key statistics, notably determinism and entropy of line length distribution, to the correlation sum as a function of embedding dimension. These expressions are obtained by deriving the transformation which generates an embedded recurrence plot from an unembedded plot. A single unembedded recurrence plot thus provides the statistics of all possible embedded recurrence plots. If the correlation sum scales exponentially with embedding dimension, we show that these statistics are determined entirely by the exponent of the exponential. This explains the results of Iwanski and Bradley [J.S. Iwanski, E. Bradley, Recurrence plots of experimental data: to embed or not to embed? Chaos 8 (1998) 861–871] who found that certain recurrence plot statistics are apparently invariant to embedding dimension for certain low-dimensional systems. We also examine the relationship between the mutual information content of two timeseries and the common recurrent structure seen in their recurrence plots. This allows time-localized contributions to mutual information to be visualized. This technique is demonstrated using geomagnetic index data; we show that the AU and AL geomagnetic indices share half their information, and find the timescale on which mutual features appear.

Use of item response theory to develop a shortened version of the EORTC QLQ-C30 emotional functioning scale

As part of a larger study whose objective is to develop an abbreviated version of the EORTC QLQ-C30 suitable for research in palliative care, analyses were conducted to determine the feasibility of generating a shorter version of the 4-item emotional functioning (EF) scale that could be scored in the original metric. We used data from 24 European cancer studies conducted in 10 different languages (n = 8242). Item selection was based on analyses by item response theory (IRT). Based on the IRT results, a simple scoring algorithm was developed to predict the original 4-item EF sum scale score from a reduced number of items. Both a 3-item and a 2-item version (item 21 'Did you feel tense?' and item 24 'Did you feel depressed?') predicted the total score with excellent agreement and very little bias. In group comparisons, the 2-item scale led to the same conclusions as those based on the original 4-item scale with little or no loss of measurement efficiency. Although these results are promising, confirmatory studies are needed based on independent samples. If such additional studies yield comparable results, incorporation of the 2-item EF scale in an abbreviated version of the QLQ-C30 for use in palliative care research settings would be justified. The analyses reported here demonstrate the usefulness of the IRT-based methodology for shortening questionnaire scales.

Measurement exchangeability and normal one-factor models

The one-factor model restricts the covariance structure of the observed variables on the basis of assumptions about their relationship with an unobserved variable. It is hard to justify these assumptions on substantive or empirical grounds. In this paper, alternative measurement models are proposed that are based on exchangeability of variables after admissible scale transformations. They provide an alternative interpretation of the model and do not involve unobserved variables. They also yield a new one-factor model for sum scales. © 2004 Biometrika Trust.

Gesundheitsbezogene Kontrollüberzeugung und Lebensqualität bei chronisch Kranken nach stationärer Behandlung mit Integrativer Medizin – eine Beobachtungsstudie

Health-Related Control Belief and Quality of Life in Chronically Ill Patients after a Behavioral Intervention in an Integrative Medicine Clinic – an Observational Study Background: In 1999 the Clinic for Internal Medicine and Integrative Medicine was founded in Essen as a regular part of the German inpatient health care system. Integrative medicine (standard internal medicine, evidence-based complementary and alternative medicine combined with intensified lifestyle modification) aims to help patients with chronic illness to cope with their condition more effectively and to achieve a health-promoting lifestyle. Techniques include cognitive restructuring, the elicitation of the relaxation response, and lifestyle education. The goal is to increase health-related quality of life (QoL) as well as control beliefs and to reduce morbidity in later life. Aim: To demonstrate changes in quality of life, lifestyle, and control beliefs after a two-week hospital stay. Methods: Uncontrolled prospective observational study with 557 consecutive hospital patients. Outcome parameters were quality of life (SF36), control beliefs (GKÜ), and daily health-related behavior (nutrition, physical activity, relaxation) on admission, at discharge, as well as 3 and 6 months after discharge. Results: Weekly physical activity increases by 29%, consumption of not recommendable foods decreases by 18%. The majority of patients (57%) engage in relaxation exercises 6 months after discharge (on admission 23%). The physical sum scale (SF36) increases from 33.9 (95% KI 32.5–35.3) on admission to 37.3 (35.8–38.9) 6 months after discharge, the mental sum scale from 41.2 (39.5–42.9) to 45.1 (43.5–46.7). The ratio internal/external control belief rises from 1.17 (95% KI 1.11–1.24) to 1.32 (1.24–1.40). Pretherapeutic ratio internal/external control belief and its increase are associated with rises in QoL. Conclusions: After integrative medicine treatment a lasting increase in QoL and lifestyle changes can be achieved. Reinforcement of internal control beliefs and own competence is possible and enhances outcomes in chronically ill patients.

A THEORY-GUIDED HEXAGONAL REPRESENTATION OF SINGLE VALUATION SYSTEMS FOR USE WITH HERMANS' SELF-CONFRONTATION METHOD

In the self-confrontation method (SCM), a person connects affect-denoting terms to important experiences or "valuations" by rating each affect on a 0-5 scale of intensity. These affects are grouped into four sum scales: Self, Other, Positive, and Negative. Six valuation types can be constructed on the basis of the scale profile of each valuation. We investigated four methods for depicting single valuation systems within a 2-dimensional plane. A study using 210 single grids showed most methods to generate high quality depictions. One "fixed" method, in particular, was considered most promising. Its form consisted of a hexagonal frame, of which the angular points represented the most extreme elements of the six valuation types. Valuation systems could then be projected against a theoretically meaningful background. Implications for practice and research with the SCM were considered.

Using item response theory to calibrate the Headache Impact Test (HIT) to the metric of traditional headache scales.

Item response theory (IRT) scoring of health status questionnaires offers many advantages. However, to ensure 'backwards comparability' and to facilitate interpretations of results, we need the ability to express the IRT score in the metrics of the traditional scales. To develop procedures to calibrate IRT-based scores on the Headache Impact Test (HIT) into the metrics of the traditional headache scales. To assess the degree to which the calibrated HIT scores agree with the observed traditional scores and lead to the same conclusions in group comparisons. We used telephone interview data (n = 1016) and Internet data (n = 1103) from general population surveys of recent headache sufferers. Analyses were conducted in four steps: (1) develop IRT models for all items, (2) for each IRT score level, calculate the expected score on each of the traditional scales (calibration), (3) adjust this calibrated score for measurement error in the IRT score, (4) for each of the traditional scales, assess agreement between calibrated HIT scores and observed scores using intraclass correlation (ICC) and evaluate the agreement of mean scores and the relative validity (RV) in discriminating among groups differing in migraine diagnosis, headache severity, and change in impact over time. For the traditional categorical questionnaire items (the Migraine Specific Questionnaire (MSQ) and the Headache Disability Inventory (HDI)) the calibrated HIT agreed with the observed traditional scores: ICC's were between 0.80 and 0.94. In RV analyses the maximum mean difference between the observed and expected scores was 1.7 points on a 0-100 scale for comparisons at one point in time. Analyses of change over time and analyses calibrating scores from the fixed-form HIT-6 to the metric of other questionnaires were also satisfactory although less precise. Analysis of non-standard questionnaire items (e.g. On how many days in the past 3 months did you have a headache, from the HIMQ and the MIDAS) required special IRT models. Agreement was less good: ICC's were between 0.56 and 0.61 and the maximum mean differences were 2.9 (on a 0-270 scale) and 3.8 (on a 0-450 scale) in RV analyses at one point in time. The ability of the calibrated scale scores to discriminate between groups was at least as good as the ability of the observed sum scales and often remarkably better. The theoretical advantage of IRT models in scale calibration is supported by our results. This approach to achieving comparability of new and widely-used scales and accelerating the accumulation of interpretation guidelines based on previous work warrant testing for measures of other generic and disease-specific concepts.