An Assessment of the Effects of Item Difficulty and Examinee Ability on the Effectiveness of LZ Appropriateness Index

This study investigated the effectiveness of LZ appropriateness index in detecting aberrant response patterns under nine combinations of item difficulty and examinee’s ability distributions, type of aberrance, and level of aberrance. Data was generated in nine combinations of item difficulty and examinee ability to simulate the responses of 2000 non-aberrant examinees’ response patterns to a 60-item test according to three-parameter model. Three uniform distributions of item difficulty were used. Two samples each consisting of 500 normal response vectors (one for spuriously low and one for spuriously high modifications) were also generated in each of the nine combinations and subjected to spurious treatment. An examinee with a spuriously high test score was simulated by selecting 20% or 10% of the examinee's original responses without replacement and changing incorrect answers to correct, but they were left unchanged if correct. An examinee with a spuriously low test score was simulated by first randomly selecting 20% or 10% of the examinee's original responses without replacement and changing correct responses to incorrect, but they were left unchanged if incorrect. LZ appropriateness index was then computed for the aberrant response vectors. The effectiveness of LZ index was evaluated by examining the extent to which it separated normal and aberrant response vectors solely on the basis of appropriateness index scores. The percentile estimates obtained for each index at each false positive rate were used as cutoff scores. The LZ index identified higher proportions of aberrant response patterns in the 20% spuriously low treatment samples than in the 20% spuriously high treatment samples. Ten percent spuriously low aberrant response samples were also found to be more detectable than the 10% spuriously high aberrant response patterns. The detection rates of the 20% and the 10% spuriously high aberrant response patterns by LZ index were found to be higher under high item difficulty parameters, and were found to be low under the low item difficulty parameters. This is not surprising as it is expected that more responses are changed from incorrect to correct and fewer responses are changed from correct to incorrect under high item difficulty parameters. The 20% and the 10% spuriously low aberrant response patterns were also more detectable under the low item difficulty parameters because more responses are changed from correct to incorrect and fewer are changed from incorrect to correct under the low item difficulty parameters. Keywords: Appropriateness index, effectiveness, maximum likelihood index, validity

Establishing the quality management baseline in the use of computed tomography machines in Kenya

The objective of this study was to assess the level of compliance to quality assurance and image quality standards in computed tomography facilities in Kenyan hospitals. A quality assurance inspection and physical image quality assessment in eighteen representative computed tomography facilities were completed. A quantitative method was developed and used to score the results obtained from the physical image quality measurements using the American Association of Physicists in Medicine (AAPM) water phantom. Inspection was done in order to establish the level of compliance with internationally recognized standards such as those stipulated in the European Guidelines Quality Criteria for Computed Tomography and the International Basic Safety Standards for Protection against Ionizing Radiation. The overall findings placed the national quality management performance at 50± 3%, while image quality and quality assurance performance were 61 ± 3% and 37 ± 3%, respectively. The quality assurance assessment benchmarked the country’s level of quality management system compliance in diagnostic radiology. During accreditation appraisal, the scrutiny of scores from each stage in the medical imaging chain per facility will encourage continual implementation of the quality improvement process

Radiation exposure in interventional procedures

The aim of this study was to estimate radiation doses patients and staff are exposed to during interventional procedures (IPs), compare them with the international diagnostic reference levels and to develop initial National Diagnostic Reference Levels. The IP survey was undertaken as the initial task of which, retrospective data were collected from the only four Kenyan hospitals carrying out interventional radiology and cardiology procedures at the time of the study. Real-time measurement of radiation dose to patients and staff during these procedures was done. To the patients, kerma-area product (KAP) and fluoroscopy time measurements were done using an in-built KAP meter, while peak skin dose (PSD) was measured using slow Extended Dose Range (EDR2. ®) radiographic films. The staff occupational doses were measured using individual thermoluminescence dosemeters. The maximum and minimum KAP values were found to be 137.1 and 4.2 Gy cm. 2, while the measured PSD values were 740 and 52 mGy, respectively. The fluoroscopic time range was between 3.3 and 70 min. The staff doses per procedure ranged between 0.05 and 1.41 mSv for medical doctors, 0.03 and 1.16 mSv for nurses, 0.04 and 0.78 mSv for radiographers and 0.04 and 0.88 mSv for clinical staff. The measured patient PSDs were within the threshold limit for skin injuries. However, with the current few IP specialists, an annual increase in workload as determined in the study will result in the International Commission on Radiation Protection annual eye lens dose limit being exceeded by 10 %. A concerted effort is required to contain these dose levels through use of protective gear, optimisation of practice and justification

The Impact of School Environment and Peer Influences on Students’ Academic Performance in Vihiga County, Kenya

The aim of this paper is to examine the relationship between both school environment and peer influences on the one hand and students’ academic performance on the other hand. The study assessed school environment factors and peer influences in terms of the level of psychological impact they have on learners. The study was based on Albert Bandura’s Social Learning Theory, which considers leaning as an interaction between environment, behaviour, and one’s psychological processes. It was a correlation study carried out in Sabatia District of Vihiga County in twenty-one public secondary schools. The respondents were selected using simple random sampling technique. Questionnaires were used to collect data, which were analyzed by multiple regressions. The study established that school environment and peer influence made significant contribution to the students’ academic performance. A school, as a learning institution and as a second home for learners, has a strong relationship with students’ academic performance. The head teacher and the teachers through their specific roles either have negative or positive influence on students’ academic performance. Therefore, the head teacher and the teachers should enhance a conducive learning environment in which the learners are free to consult them when in need, provide adequate learning facilities and arouse interest in the learners to work hard. Peer level factors also have a relationship with students’ academic performance. It is hoped that the findings of this study will be useful to teachers, principals and parents to gain more insight into the psychosocial factors that affect students’ academic performance and therefore help improve their academic performance. Keywords: Impact, School Environment, Peer Influences, Students Academic Performance, Vihiga County, Keny

Does Structural Power Matter? Board Attributes and Firm Performance: Moderated by CEO Duality

Purpose- The study investigates the moderating role of Chief Executive Officer Duality onboard attributes and firm performance of companies listed in Kenya. Design/Methodology- The research used a longitudinal research design. Panel data were derived from published accounts for sixteen years that is from 2002-2017. IGLS regression models were used to test the hypothesis. Findings- The empirical results indicated that the independence of the board, the size of the board, and the duration in which the board member served the organization positively influence the firm performance. However, CEO duality does not moderate the relationship. Practical Implications- Regulatory bodies such as NSE and CMA in Kenya should ensure that listed firms have more independent directors serving a board, ensure a reasonable size of the board and increase the board tenure to enhance firm performance. Further, the combined roles of the CEO and chairman may not influence the efficiency of the board in the Kenyan context

Establishing a quality assurance baseline for radiological protection of patients undergoing diagnostic radiology

Background. The wide use of ionising radiation in medical care has resulted in the largest man-made cause of radiation exposure. In recent years, diagnostic departments in Kenya have adapted the high-speed film/screen combination without well-established quality control, objective image quality criteria, and assessment of patient dose. The safety of patients in terms of justification and the as-low-as-reasonably-achievable (ALARA) principle is inadequate without quality assurance measures. Aim. This study assessed the level of film rejects, device performance, image quality and patient dose in 4 representative hospitals using high-speed film/screen combination. Results. The X-ray equipment quality control tests performance range was 67% to 90%, and 63% of the radiographs were of good diagnostic value. The measured prevalent chest examination entrance surface dose (ESD) showed levels above the international diagnostic reference levels (DRLs), while lumbar spine and pelvis examination was the largest source of radiation exposure to patients. Conclusion. The optimisation of patient protection can be achieved with optimally performing X-ray equipment, the application of good radiographic technique, and continuous assessment of radiographic image quality

Seq-ing improved gene expression estimates from microarrays using machine learning

BACKGROUND: Quantifying gene expression by RNA-Seq has several advantages over microarrays, including greater dynamic range and gene expression estimates on an absolute, rather than a relative scale. Nevertheless, microarrays remain in widespread use, demonstrated by the ever-growing numbers of samples deposited in public repositories. RESULTS: We propose a novel approach to microarray analysis that attains many of the advantages of RNA-Seq. This method, called Machine Learning of Transcript Expression (MaLTE), leverages samples for which both microarray and RNA-Seq data are available, using a Random Forest to learn the relationship between the fluorescence intensity of sets of microarray probes and RNA-Seq transcript expression estimates. We trained MaLTE on data from the Genotype-Tissue Expression (GTEx) project, consisting of Affymetrix gene arrays and RNA-Seq from over 700 samples across a broad range of human tissues. CONCLUSION: This approach can be used to accurately estimate absolute expression levels from microarray data, at both gene and transcript level, which has not previously been possible. This methodology will facilitate re-analysis of archived microarray data and broaden the utility of the vast quantities of data still being generated

Antimicrobial properties of hugonia casteneifolia and its potential use for the control of opportunistic infections

No Abstrac

Economic Analysis of Spatial Integration of Pulse Market in Ethiopia; A case of Selected Pulse Market in Ethiopia

In order to solve the problem of food insecurity the Government of Ethiopia has adopted different strategies since the introduction of agricultural extension services in the early 1970s, to improve the performance of the agricultural sector. However, most of this strategy has focused on how to increase agricultural productivity at the farm level through the dissemination of improved production technologies, while the marketing aspect has been given less attention.  Considering this, in order to improve the market efficiency, significant numbers of empirical studies have been conducted on market integration but they focused mainly on cereal[1] market while pulse market has not been given adequate attention. Yet pulse is the third largest export crop in the country and generates USD 232.5 million annually and it has been showing a significant growth in export and production in the last decade. The study assesses the price transmission of selected pulse market in Ethiopia using monthly wholesale price data in Birr/Quintal covering the period January 2003 to December 2013 for Horse beans and Chickpeas from Ethiopian Grain Trade Enterprise. The stationarity of the price data was tasted using Augmented Dickey-Fuller (ADF) and Phillips-Perron tests. To test the co integration level Engle and Granger (Engle and Granger, 1987) test were applied. To identify which market price change will cause a price change in other market, Granger Causality model was used. The selected markets are Addis Ababa as a central market; Adama as closest market based on distance form central market; Diredewa as remotest both for Horse beans and Chickpeas. While Desse and Gonder as main producing market of Horse beans and Chickpeas respectively. The finding indicates that all the selected markets are co integrated. However, Addis Ababa- Desse for the case of Horse beans and Addis Ababa- Gonder for Chickpeas markets have strongly integrated.  Concerning causality, Addis Ababa - Desse, Addis Ababa - Adama, Desse - Diredawa markets are unidirectional while Desse - Adama are bidirectional for horse bean. However, for Chickpeas, all the selected markets do not Granger Cause each other in both directions except between Diredawa - Adama which were unidirectional. This implies that there is a need of improvement in market information systems especially to producing markets, and also timely accurate price information for trade participant to distribute commodities from surplus area to deficit markets. Key Words: Pulse, Ethiopia, Granger Causality, price transmission [1] Studies focused mainly on cereal market: Maize, Wheat, Sorghum and Teff (Negassa, 1998; Negassa et al., 2004; Getnet et al., 2005; Getnet, 2007; Tadesse and Shively, 2009 and Sinishaw, 2013)