Up to date, it is unclear how Choice-Based Conjoint (CBC) models perform in terms of forecasting (external) real world aggregate shop data. In this contribution, we measure the performance of a Latent Class CBC model - not with an experimental holdout sample - but with aggregate real world scanning data. We find that the CBC model does not accurately predict real world market shares. In order to improve the forecasting performance, we propose a correction scheme based on external scanner data. Our analysis based on 8 brands shows that the use of the proposed correction vector improves the performance measure considerably. (author's abstract) / Series: Working Papers SFB "Adaptive Information Systems and Modelling in Economics and Management Science"

Dr. Ronald Cervero (1985) identified learner motivation, the nature of the change, the social system of the organizational climate, and the educational program as factors affecting the application of learning to professional practice. A repeated measures research design was used to measure stability over time of instruments developed to measure variables in Cervero's model. Participants, N=27) graduate students, completed the instruments, "New Ideas and You" which measures learner's motivation to change, "The Nature of Change" which measures the learner's perception of the proposed change, and "Organizational Climate of the Social System" which measures the learner's perception of the social system's affect on the implementation of change. Staff nurses (N=27) completed the instrument "Continuing Education Offering Evaluation" which measures the learner's perception of the educational offering. Participants then completed the instruments again in three weeks. Procedures for the protection of human subjects were followed. The test-retest reliability coefficients were: "New Ideas and You," r=.72 L)-.01; "The Nature of Change," r.84 p=.01; "Organizational Climate of the Social System," r.83 p=.01; "Continuing Education Offering Evaluation," r.91 p=.01. The significance of this study was the initial establishment of stability over time of instruments developed to measure specific factors that affect the application of newly gained knowledge to nursing practice. Establishing reliability coefficients of instruments to measure the variables in Cervero's model is a step forward in the investigation of the larger question, "Does continuing education change practice?" / School of Nursing

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The pupose of this study was to examine the validity of the Differential Abilities Scale with a gifted sample. Subjects consisted of 111 students identified as gifted by Indiana S-4. They were in grades 1 thru 6 and ranged in age from 6-8 to 12-11 with a mean age of 9-8. There were 60 females and 51 males who participated. Approximately, 1% of the population was minority which closely resembled the school population. Data from previously administered WISC-III and WIAT (The Psychological Corporation, 1992) were available for 21 of the 111 students.The first aspect of this study was to assess the construct validity of the DAS through investigation of the internal structure. Several different models were proposed. These analyses revealed that the proposed models were not good explanations of the relationships among obtained scores because convergence could not be obtained. A respecified two factor model was obtained where loadings on a Verbal Factor were constrained as recommended by Maxwell (1977). For this sample of gifted students a two-factor model with the first factor being primarily composed of Word Definitions was found to be a tenable one for the DAS.The second aspect of this study was to examine the convergent and predictive validity of the DAS by comparing these scores with the WISC-III and WIAT scores. Verbal factors for the two intelligence tests were the most highly correlated. Although there is overlap between the two intelligence measures, each test measures something unique. While one might expect these two instruments would not correlate perfectly, this correlation is lower than predicted.The DAS cognitive portion was more highly related to the other ability measure, the WISC-III, than it was to achievement as measured by the WIAT. In addition, achievement portions of both instruments were more highly related than they were to the ability measures. / Department of Educational Psychology

Tests of sensory and motor function are widely used by clinicians and researchers in neurology, psychiatry, and neuropsychology. Less than perfect performance on many of these tests may be considered pathognomonic of central nervous system dysfunction. Unfortunately, differences across practitioners in specific test selection, administration procedures, and scoring criteria have resulted in inconsistencies which confound attempts to study the incidence and patterns of deficits (Adams & Victor, 1993; Glick, 1993). Although as a group psychologists favor standardized, quantitative instruments, the field has lacked a comprehensive, standardized sensory and motor battery. That psychologists have not developed such a battery may reflect the notion that pathognomonic signs are ambiguous and unstable (Buchanan & Heinrichs, 1989) and the fact that some traditional test development procedures are often inappropriate.For the Dean-Woodcock Sensory and Motor Battery, Dean and Woodcock (1994) selected measures representative of those included in the traditional neurological examination.Measures of subcortical function, unavailable in the major neuropsychological batteries, were included to allow differentiation with right hemisphere impairment.Using standard procedures for administration and scoring, this study gathered preliminary data regarding the incidence of pathognomonic signs in a normal adult population, identified items with difficulty levels likely to result in overidentification of abnormality, and estimated the interrater agreement and interrater reliability for items and tests most vulnerable to subjective interpretation. Data analysis reflected consideration of Franzen's (1989) argument that reliability can be better understood through use of multiple estimation strategies and Cicchetti's argument that data needs to be considered at "finer levels of molecular analysis" (p.621). In addition to investigating interrater agreement, this study applied generalizability theory which allows for simultaneous estimation of the relative proportion of variance contributed by multiple sources and their interactions.Results suggested adequate to excellent rater agreement and reliability (i.e., generalizability). Also, with minor modification of specific items, generalizability of items may be expected to increase. Future studies should sample from a more heterogenous general population and specific clinical populations. / Department of Educational Leadership

Little is known about infants’ ability to deal with commonly encountered situations in which speech from one individual occurs simultaneously with that of others. Previous research has shown that while age of the infant and intensity of the background matter, so does the number of background speakers. The read-aloud multi-talker speech used in previous studies is perceptually different from conversational speech typically encountered by infants. To test generalizability, this study used a background of ecologically valid multi-talker speech. Using the head-turn preference procedure, infants were presented with passages of background noise with and without target infant-directed speech at a 10 dB SNR. Results show that while 9-month-olds prefer passages containing target speech with a white noise background, both 9- and 12-month-olds failed to show a preference with a multi-talker background. This inability to segregate speech streams under ecologically valid conditions demonstrates the adversity infants face to learn their community’s language.

Institutions of higher learning are currently faced with the crisis of finding appropriate criteria for undergraduate admission. This concern has been sparked by the fact that matriculation grades are no longer seen as an accurate reflection of students' academic potential. As tertiary education is becoming more expensive, it is therefore becoming more and more important to select only students who have a realistic chance of being successful in their studies. The main aim of this study is to validate the Situation Specific Evaluation Expert (SPEEX) as a predictor of academic success of first year students of Mechanical Engineering at the Vaal Triangle Technikon. The design used in this study is a non-experimental correlational design. This design was selected because the investigation of this study is aimed at determining the presence or absence of the relationship between the independent and dependent variables without specific reference to causality. The sample of this study consisted of a total of 140 mechanical engineering student at the Vaal Triangle Technikon. This sample was the total number of students from the Mechanical Engineering department who enrolled for mechanical engineering courses for the year 2000. The sample consisted of 94% males and females 6% females. Subject matter experts from industry as well as those involved in the training of Mechanical Engineering at the Vaal Triangle Technikon selected competencies, which were hypothesised to be indicative of a potentially successful student. Based on the selected competencies the assessment battery was compiled with the selected indices being considered as predictor variables. A multiple regression analysis was performed on data in order to establish the predictive validity of the assessment battery. SPEEX 2502 (Language proficiency) consistently showed a positive correlation on the prediction of academic success. / Thesis (MA (Industrial Psychology))--North-West University, Potchefstroom Campus, 2004.

Nurses' working environment, together with their patient relationships, can elicit emotions which they will need to manage in order to perform successfully in their daily work activities. It is for this reason that it is crucial that sound emotional intelligence measures should be developed which hospitals can utilise to identify emotionally intelligent individuals for emotionally laden jobs or even to identify their developmental needs within the area of emotional intelligence. The objective of this study was to investigate the psychometric properties of the Emotional Intelligence Scale (EIS) developed by Schutte and colleagues in 1998 within a nursing environment. A convenience random sample of 5 11 nurses was taken from hospitals located in the areas of Klerksdorp, Potchefstroom, Krugersdorp, Johannesburg and Pretoria. The EIS was used as a measuring instrument. Cronbach alpha coefficients, Pearson-product correlation coefficients and MANOVAS were used to analyse the data. The results showed a 5-factor solution for the EIS, which explained 50,04% of the total variance. All of the five dimensions had adequate internal consistencies, except for the Negative Emotions dimension. Lastly, group differences were identified between personnel area and emotional intelligence, as well as between race and emotional intelligence levels. Recommendations were made for future research. / Thesis (M.Com. (Industrial Psychology))--North-West University, Potchefstroom Campus, 2006.

Social support has been proven to play a major role in the well-being of an individual. Unfortunately, the conceptualisation of the construct is vague and many authors disagree about the various properties and dimensions of the construct. Seen from a health-related perspective, social support can be regarded as divided into two main spectrums, the main-effect model and the stress-buffering model. The main-effect model proposes that social support has a beneficial effect, whether or not an individual is under stress, while the stress-buffering model proposes that social support buffers an individual from potentially pathological influences. The construct is furthermore conceptualised as consisting of distinct structural, functional and perceptual dimensions. The aim of the research was to develop an instrument which would incorporate all three of these dimensions and could be proven valid and statistically reliable. A cross-sectional survey design was used. An availability sample of qualified educators in the North-West Province of South Africa was used. The Social Support Survey was developed as a measuring instrument and administered along with a biographical questionnaire. Descriptive statistics and inferential statistics were used to analyse the data. Contrary to expectation, factor analysis indicated that the four factors regarding the characteristics of the support, as well as the five factors regarding the types of support, were clustered around the source of support. This might be due to the Likert-scale matrix design of the questionnaire, which required participants to answer a wide range of questions regarding the type, importance, amount, adequacy and accessibility of support. By way of conclusion, recommendations were made. / Thesis (M.Com. (Industrial Psychology))--North-West University, Potchefstroom Campus, 2008.

Adolescence proves to be one of the most vulnerable development stages in the life of humans and therefore dietary assessment of this group is important, but complex. This is due to rapid growth during puberty and the development of new eating patterns that influence dietary intake. Adequate dietary intake in this age group is crucial, since adverse effects such as iron deficiency anemia, inadequate growth and dental caries can occur. Furthermore, dietary imbalance is a significant risk factor that can lay the groundwork for developing preventable complications in late adolescence and adult life such as non-communicable chronic diseases including obesity and diabetes mellitus type II and certain cancers, all leading causes of morbidity and mortality. Given the vulnerability of adolescents in terms of dietary intake, understanding their dietary intake is crucial. Dietary assessment of adolescents is influenced by social, physiological and psychological changes making accurate measurement of this group difficult. Hence, it is of fundamental importance to find a golden standard in terms of a dietary assessment method to use in this group. Several international studies investigated validity and reproducibility of the dietary intake of adolescents, measured with different dietary assessment methods. However, in South Africa only three validity and reproducibility studies have been published and none of them focused exclusively on adolescents. Since the validity of the results of dietary assessment methods of international studies cannot be extrapolated to South African black adolescents, this study emanated from the need to investigate whether multiple 24-hour recalls are valid and reproducible when used to assess the dietary intakes of black adolescents in a convenience sample of grade eight learners from a high school in a township in the North West Province. The study was nested in the multidisciplinary "Physical, Activity in the Young" (PLAY) study. Firstly, the optimal number of 24-hour recalls was determined by calculation of reproducibility coefficients for energy, selected nutrients and food groups. Results showed that four repeated 24-hour recalls provided the optimal reproducibility for black peri-urban South African adolescents. Secondly, the search for a reference method to compare energy intake against energy expenditure led to an investigation into basal metabolic rate equations and physical activity factors with the intention of estimating the energy expenditure. Validity of reported energy intake assessed by multiple 24-hour recalls and estimated energy expenditure was tested using the Pearson correlation coefficient and the dependent t-test. The Pearson correlation test revealed low associations between energy intake and energy expenditure for boys (0.32) and girls (0.17), while the dependent t-test of the energy intake between the different measured occasions showed little difference, which could be explained by the high within participant variation and lower variation between the different participants. The low correlation coefficients showed that there was no association between reported energy intake and mean estimated energy expenditure; thus also no agreement. As a result, multiple 24-hour recalls measured over two years with only five 24-hour recalls did not give a valid measurement of the energy intake of black peri-urban adolescents. Lastly, the ratio of reported energy intake over energy expenditure was evaluated against the energy cut-off points, specifically calculated for age and ethnic group. It indicated that 85% of the participants underreported their energy intake. These results could have been influenced by the estimated basal metabolic rate equations that could have estimated the basal metabolic rate of this group incorrectly or could be due to the inability of the group to recall their physical activity levels correctly. Therefore it is recommended that further validity studies regarding dietary intake need to be performed on adolescents. It is suggested that energy expenditure as a reference method should be measured by using a calorimeter or the doubly labeled water method and then compared with the reported energy intake. Analysing different biochemical determinants of nutritional intake could also be used as an objective reference method to assess the validity of dietary data obtained from questionnaires. / Thesis (Ph.D. (Dietetics)--North-West University, Potchefstroom Campus, 2009.