Item nonresponses in educational and psychological measurement

The question of how to handle missing responses in psychological and educational measurement has been repeatedly and controversially debated for decades. Even in highly respected international studies and large scale assessments, such as the PISA (Program for International Student Assessment), TIMSS (Third International Mathematics and Science Study), and PIRLS (Progress in International Reading Literacy Study) a generally accepted methodology for missing data is still lacking. Since the late 1990s multidimensional item response theory (MIRT) models for item nonresponses have been developed. These models become quickly complex in application and rest upon assumptions that are usually not critically addressed. Although statistical theory of missing data suggests adequate handling of missing responses to avoid inefficient and biased parameter estimation, there is empirical evidence that IRT-based parameter estimation is fairly robust against missing responses. That may question the need for sophisticated IRT model-based approaches. For that reason this thesis consists of two major parts. After the introduction of the missing data theory in the context of educational and psychological measurement, the impact of item nonresponses to item- and person parameter estimates are examined in the first part. In the second part existing approaches to handle missing responses are scrutinized and further developed. The different methods are critically compared and recommendations will be given as to which approaches are appropriate. The considerations are confined to dichotomous items that are still common in many tests and assessments. The impact of missing responses to item and person parameter estimates was shown analytically and empirically using simulated data. The results show clearly that ignoring systematic missing data leads to biased item and person parameter estimates in IRT models. The findings highlight the need for appropriate methods to handle item nonresponses properly. It could be shown that simple ad-hoc methods such as incorrect answer substitution (IAS) or partially correct scoring (PCS) are not justifiable theoretically and threaten the test fairness and the validity of test results. The nominal response model (NRM) for item nonresponses is an alternative approach that was examined. In this model item nonresponse are regarded as an additional response category. However, the NRM rests upon strong assumptions and, therefore, its applicability is limited. MIRT models for missing responses rank among modern model-based approaches. The underlying rationale of these models is outlined in detail. It could be shown that MIRT models for item nonresponses are special cases of selection models and pattern mixture models for latent trait models with particular assumptions. Different MIRT models are discussed in the literature and are typically regarded to be equivalent. Two classes of MIRT models can be distinguished: between- and within-item multidimensional IRT models. In this thesis it is shown that these models are not equivalent per se. Typically, the question of model equivalence is considered with respect to the model-fit. In models for item nonresponses the criterion of model-fit is insufficient to judge equivalence of alternative models. The equivalence in the construction of the latent variable of interest and the bias reduction are additional criteria that need to be considered. A common framework of IRT models for item nonresponses is presented. Different between- and within-item multidimensional IRT models are rationally developed, taking the issue of model equivalence into account. Between-item multidimensional models are easy to specify and to interpret and are recommended as the models of choice. The disadvantage of MIRT models for item nonresponses is their complexity. Besides the latent variables of theoretical interest, a latent response propensity is introduced to model the missing data mechanism. Typically, unidimensionality of the latent response propensity is assumed in application. This is a strong and often untested assumption. It could be demonstrated that MIRT models fail to correct for missing data if multidimensionality of the latent response propensity is not taken into account. Hence, the number of manifest and latent variables can become fairly large in MIRT models for item nonresponses. Unfortunately, high-dimensional MIRT models are still computationally challenging. For that reason more parsimonious and less demanding latent regression IRT models and multiple group IRT models are derived as an alternative. The relationship between these models and the MIRT models is demonstrated. Finally, it is shown that missing responses due to omitted and not-reached items have different properties suggesting different treatments of them in IRT measurement models. Whereas omitted responses can be appropriately handled by MIRT models, not-reached items need to be taken into account by latent regression models. Since real data sets typically suffer from both, omitted and not-reached items, a joint model is introduced that account for both types of missing responses. The thesis ends with a final discussion in which the findings are summarized and recommendations for real applications are given. Unsolved problems and remaining research questions are outlined

Chemical and nutritional content of Opuntia ficus-indica (L.)

Opuntia ficus-indica (L.) fruit pulp was analyzed for its chemical and nutritional content and the results compared with those of the same species from other parts of the world. The analysis included those for: Moisture and ash contents, crude fibre, energy values, non-reducing sugars, crude protein and vitamin C. Total carbohydrates were obtained by calculation. Results show no major variation in moisture content, amount of ash except in the Kenyan sample (A), which had a high value of 4.03 ± 0.52)%. Vitamin C varied from the three reported sources whereas crude fat was the same in all except 0.40% in sample A. Crude fiber varied and calorific value only reported in A was 3.77 kcal/g. Carbohydrates varied widely between 12 to 92%. All analyzed minerals varied, but Pb and Cd were absent. From this study, it is evident that the nutritional composition of Opuntia ficus-indica (L.) varies in regards to age and season. However, irrespective of the origin or variety, these fruits are a good natural reservoir of energy whose nutritive components and antioxidants such as vitamin C, can be used as a food supplement.Keywords: Kenya, nutritional composition, Opuntia ficus-indica (L.) fruits.African Journal of Biotechnology Vol. 12(21), pp. 3309-331

Can A Single Exposure To The Resource-Event-Agent Framework Enhance Data Modeling Performance?

Due to the widespread use of technology, it is becoming increasingly critical that accounting students have the ability to document accounting information systems (AIS).  This skill is important for understanding the information system, mapping business processes, and understanding systems’ controls.  The present study reports on an experiment designed to investigate the effects of a single exposure to the Resource-Event-Agent (REA) framework on students’ data modeling performance.  The results of the experiment indicate that accounting students who receive a single, scripted exposure to the REA framework perform better on data modeling tasks than students with no exposure to the REA framework.  This has important implications for accounting educators as they develop classroom instruction and administrators as they contemplate an appropriate emphasis on data modeling in the accounting curriculum

The Influence of Director Stock Ownership and Board Discussion Transparency on Financial Reporting Quality

Seventy-two active corporate directors participate in an experiment where management insists on aggressive recognition of revenue, but the chief audit executive proposes a more conservative approach. Results indicate interactive effects of director stock ownership and the transparency of director decisions. Stock-owning directors are more likely to oppose management’s attempts to manage earnings when transparency increases. For non-stock owning directors, however, increasing transparency does not affect the likelihood that directors oppose management’s attempts to manage earnings. The current study challenges suppositions that equate director stock ownership with improved financial reporting and higher corporate governance quality, and it provides evidence that increased transparency is beneficial when director compensation plans threaten director independence

The Effects of Disclosure Type and Audit Committee Expertise on Chief Audit Executives’ Tolerance for Financial Misstatements

This study involves an experiment where 73 Chief Audit Executives and deputy Chief Audit Executives determine the amount of adjustment required to correct a misstatement. We manipulate the financial reporting location of the misstatement (recognized vs. disclosed) and the level of audit committee expertise (high vs. low). The results indicate that financial reporting location has significant effects on internal auditors’ decisions to correct misstatements. Specifically, internal auditors are more willing to waive disclosed misstatements relative to recognized misstatements. Contrary to expectations, the results do not indicate that increased audit committee expertise and associated increases in audit committee members’ perceived powers cause internal auditors to be less willing to waive misstatements

Remote sensing of volcanic ash clouds using special sensor microwave imager data

Measurements from the satellite-based special sensor microwave imager (SSM/I) were used to collect passive microwave radiation (19–85 GHz) for the August 19, 1992 (UT date), Crater Peak/Spurr volcanic cloud. This eruption was also imaged by a ground-based C-band radar system at Kenai, Alaska, 80 km away, and by the thermal infrared channels of the polar-orbiting advanced very high resolution radiometer (AVHRR). The SSM/I sensor detects scattering of Earth-emitted radiation by millimeter size volcanic ash particles. The size of ash particles in a volcanic ash cloud can be estimated by comparing the scattering at different microwave frequencies. The mass of particles in the volcanic ash cloud can be estimated by using a theoretical method based on Mie theory or by adapting the empirical methods used for estimating rainfall rates and accounting for the different dielectric constants of volcanic ash and raindrops. For the August 19, 1992, Crater Peak/Spurr eruption, the SSM/I-based estimate of ash fallout mass (1.3 × 109 − 3 × 1010 kg) was 4%–85% of the mass fallout measured in the field. Like weather radar systems, the SSM/I offers the ability to sense young volcanic ash clouds during and immediately following (within 30 min) actual eruptions. Because most volcanoes are out of range of weather radar systems, the SSM/I may be an important tool for determining the magnitude, initial trajectory, and potential fallout mass of eruptions. The SSM/I may therefore play a role in mitigating volcanic cloud hazards for aircraft, determining masses where ground sampling is not possible, and in issuing fallout warnings for communities downwind of volcanic eruptions

The need for speech and language therapy intervention for infants and toddlers with tracheostomies : a retrospective study

There has been a worldwide increase in the number of tracheostomies performed on the paediatric population, particularly during the first year of life, which has also been evident at Red Cross Children’s Hospital in South Africa. Infants and toddlers with tracheostomies present with multiple risk factors for having or developing dysphagia and/or communication difficulties, due to the effects of the tracheostomy on the development of feeding, speech and communication, as well as the underlying medical conditions that necessitated the tracheostomy, and associated medical, social and environmental factors. There is, however, a dearth of literature in the area of paediatric tracheostomies in the South African context, particularly with regard to feeding and communication. The purpose of this study was to determine the incidence and describe the nature of dysphagia and communication difficulties in infants and toddlers with tracheostomies in the South African context, and detail the need for speech-language therapy intervention. It also attempted to determine whether there was an association between the underlying medical condition and the incidence of dysphagia and/or communication difficulties. A retrospective, descriptive survey of the folders of infants and toddlers with tracheostomies within the age range of 0 – 3 years from 2002 – 2004 at Red Cross Children’s Hospital was conducted. A checklist for dysphagia and communication difficulties in infants and toddlers with tracheostomies was developed and used to collect data from participants’ medical records. Results indicated that 80% of the study population presented with dysphagia. Oral phase difficulties were documented in 81.25%, pharyngeal phase difficulties in 60.9% and oesophageal phase difficulties in 79.7% of the dysphagic sample. Communication difficulties were recorded in 94% of the sample population. Speech production difficulties were documented in 78%, receptive language delays in 87% and expressive language delays in 96% of the sample population with communication difficulties. No statistically significant association was established between the underlying medical condition and the incidence of either dysphagia or communication difficulties. The results in the present study support the limited available literature, and the need for early speech-language therapy intervention for infants and toddlers with tracheostomies.Dissertation (M (Communication Pathology))--University of Pretoria, 2007.Speech-Language Pathology and AudiologyM (Communication Pathology)unrestricte

The Elements of Early New Orleans Jazz

This paper discusses the development of jazz that occurred in the Storyville district of New Orleans. Bernard Norman Rose explores the history of the area and the influences that resulted in a synthesis of music

Live Trap Preference Among Grassland Mammals

In two independent studies, small mammals of grassland communities in eastern Kansas, when given a choice, preferred Fitch to Sherman live traps. Except for the harvest mice in the demographic study, the type of preferred trap and magnitude of selection was remarkably comparable, with microtines showing slight, and cricetines strong, preferences overall. The merits of each type of trap are compared, and related to season, weather, prior experience, and trap-associated mortality

Why Financial Executives Do Bad Things:The Effects of the Slippery Slope and Tone at the Top on Misreporting Behavior

This paper employs theory of normal organizational wrongdoing and investigates the joint effects of management tone and the slippery slope on financial reporting misbehavior. In Study 1, we investigate assumptions about the effects of sliding down the slippery slope and tone at the top on financial executives' decisions to misreport earnings. Results of Study 1 indicate that executives are willing to engage in misreporting behavior when there is a positive tone set by the Chief Financial Officer (CFO) (kind attitude toward employees and non-aggressive attitude about earnings), regardless of the presence or absence of a slippery slope. A negative tone set by the CFO does not facilitate the transition from minor indiscretions to financial misreporting. In Study 2, we find that auditors evaluating executives' decisions under the same conditions as those in Study 1 do not react to the slippery slope condition, but auditors assess higher risks of fraud when the CFO sets a negative tone. Overall, our results indicate that many assumptions about the slippery slope and tone at the top should be questioned. We provide evidence that pro-organizational behaviors and incrementalism yield new insights into the causes of ethical failures, financial misreporting behavior, and failures of corporate governance mechanisms