REWEIGHTING DATA IN THE SPIRIT OF TUKEY: USING BAYESIAN POSTERIOR PROBABILITIES AS RASCH RESIDUALS FOR STUDYING MISFIT

A new variant of the iterative "data = fit + residual" data-analytical approach described by Mosteller and Tukey is proposed and implemented in the context of item response theory psychometric models. Posterior probabilities from a Bayesian mixture model of a Rasch item response theory model and an unscalable latent class are expressed as weights for the original data. The data weighted by the units' posterior probabilities for the unscalable class is used for further exploration of structures. Data were generated in accordance with departures from the Rasch model that have been studied in the literature. Factor analysis models are compared with the original data and the data as reweighted by the posterior probabilities for the unscalable class. Eigenvalues are compared with Horn's parallel analysis corresponding to each class of factor models to determine the number of factors in a dataset. In comparing two weighted data sets, the Rasch weighted data and the data were considered unscalable, and clear differences are manifest. Pattern types are detected for the Rasch baselines that have different patterns than that of random or systematic contamination. The Rasch baseline patterns are strongest around item difficulties that are closest to the mean generating value of è's. Patterns in baseline conditions are weaker as they depart from a item difficulty of zero and move toward extreme values of ±6. The random contamination factor patterns are typically flat and near zero regardless of the item difficulty with which it is associated. Systematic contamination using reversed Rasch generated data produces alternate patterns to the Rasch baseline condition and in some conditions shows an opposite effect when compared to the Rasch patterns. Differences can also be detected within the residually weighted data between the Rasch generated subtest and contaminated subtest. In conditions that have identified factors, the Rasch subtest often had Rasch patterns and the contaminated subtest has some form of random/flat or systematic/reversed pattern

Plant and Animal Pathogen Recognition Receptors Signal through Non-RD Kinases

Plants and animals mediate early steps of the innate immune response through pathogen recognition receptors (PRRs). PRRs commonly associate with or contain members of a monophyletic group of kinases called the interleukin-1 receptor-associated kinase (IRAK) family that include Drosophila Pelle, human IRAKs, rice XA21 and Arabidopsis FLS2. In mammals, PRRs can also associate with members of the receptor-interacting protein (RIP) kinase family, distant relatives to the IRAK family. Some IRAK and RIP family kinases fall into a small functional class of kinases termed non-RD, many of which do not autophosphorylate the activation loop. We surveyed the yeast, fly, worm, human, Arabidopsis, and rice kinomes (3,723 kinases) and found that despite the small number of non-RD kinases in these genomes (9%–29%), 12 of 15 kinases known or predicted to function in PRR signaling fall into the non-RD class. These data indicate that kinases associated with PRRs can largely be predicted by the lack of a single conserved residue and reveal new potential plant PRR subfamilies

A Comparison of the Two-Option Versus the Four-Option Multiple-Choice Item: A Case for Fewer Distractors

Multiple choice test items typically consist of the key and 3-4 distractors. However, research has supported the efficacy of using fewer alternatives. Haladyna and Downing (1993) found that it is difficult to write test items with more than one plausible distractor, resulting in items with a correct answer and one alternative, also known as the alternate choice (AC) format. We constructed two 32-item tests; one with four alternatives (MC4) and one with two (AC), using an inter-judge agreement approach to eliminate distractors. Tests were administered to 138 personnel working for a U.S. Government agency. Testing time was significantly less and scores were higher for the AC test. However, score differences disappeared when both forms were corrected for guessing. There were no significant differences in test difficulty (mean p-values). The corrected KR-20 reliabilities for both forms, after applying the Spearman-Brown formula, were AC = .816 and MC4 = .893. We discuss the results with respect to the resources spent writing and reviewing test items, and in more broadly sampling a content domain using the AC format due to reduced testing times

An Investigation of Chi-Square and Entropy Based Methods of Item-Fit Using Item level Contamination in Item Response Theory

New variants of entropy as measures of item-fit in item response theory are investigated. Monte Carlo simulation(s) examine aberrant conditions of item-level misfit to evaluate relative (compare EMRj, X2, G2, S-X2, and PV-Q1) and absolute (Type I error and empirical power) performance. EMRj has utility in discovering misfit

Understanding online K-12 students through a demographic study

Online K-12 learning opportunities have proliferated, but much remains to be understood about the characteristics of participating students. This study presents a demographic profile of fulltime, K-12 online learners today and compares them with public school students nationwide in the United States. The data was collected from a parent survey that produced 119,155 valid responses/records for students enrolled full-time in online K-12 public schools in 43 states. The study shows that the online student population includes somewhat more females than males, and more middle school than elementary or high school students. White students are overrepresented among full-time online learners compared with their share of the nationwide student population, while Hispanic/Latino and Asian/Pacific Islander students are underrepresented. Gifted and talented students and English language learners (ELLs) are also underrepresented. These data provide a baseline for more detailed explorations and can assist practitioners, policy makers, and researchers in making important decisions about online education that have implications for all students

The 2007 Analysis of Information Remaining on Disks offered for sale on the second hand market

All organisations, whether in the public or private sector, increasingly use computers and other devices that contain computer hard disks for the storage and processing of information relating to their business, their employees or their customers. Individual home users also increasingly use computers and other devices containing computer hard disks for the storage and processing of information relating to their private, personal affairs. It continues to be clear that the majority of organisations and individual home users still remain ignorant or misinformed of the volume and type of information that is stored on the hard disks that these devices contain and have not considered, or are unaware of, the potential impact of this information becoming available to their competitors or to people with criminal intent. This is the third study in an ongoing research effort that is being conducted into the volume and type of information that remains on computer hard disks offered for sale on the second hand market. The purpose of the research has been to gain an understanding of the information that remains on the disk and to determine the level of damage that could, potentially be caused, if the information fell into the wrong hands. The study examines disks that have been obtained in a number of countries to determine whether there is any detectable national or regional variance in the way that the disposal of computer disks is addressed and to compare the results for any other detectable regional or temporal trends. The first study was carried out in 2005 and was repeated in 2006 with the scope extended to include additional countries. The studies were carried out by British Telecommunications, the University of Glamorgan in the UK and Edith Cowan University in Australia. The basis of the research was to acquire a number of second hand computer disks from various sources and then determine whether they still contained information relating to a previous owner or if information had been effectively erased. If they still contained information, the research examined whether it was in a sufficient volume and of enough sensitivity to the original owner to be of value to either a competitor or a criminal. One of the results of the research was that, for a very large proportion of the disks that were examined, there was significant information present and both organisations and individuals were potentially exposed to the possibility of a compromise of sensitive information and identity theft. The report noted that where the disks had originally been owned by organisations, they had, in most cases, failed to meet their statutory, regulatory and legal obligations. In the third and latest study, conducted in 2007, the research methodology of the previous two studies conducted was repeated, but in addition to Longwood University in the USA joining the research effort, the scope was broadened geographically and the focus was extended to determine what changes had occurred in the availability of sensitive information might be occurring over time

Using journals to assess non-STEM student learning in STEM courses: A case study in cybersecurity education

Embry-Riddle Aeronautical University offers a minor course of study in cybersecurity as an option in our undergraduate Homeland Security program. Since the students are, by and large, social scientists, the focus of the program is to build hyper-awareness of how cybersecurity integrates within their professional aspirations rather than to provide cybersecurity career-level proficiency. Assessing student learning of the technical aspects cannot be performed using traditional tests, as they would not properly measure what the students are learning in a practical sense. Instead, we employ journals and self-reflection to ask the students to express and demonstrate their learning. Although somewhat harder to grade, the journals have huge benefits to the learning environment as well as to actual learning

BLOGS: ANTI-FORENSICS and COUNTER ANTI-FORENSICS

Blogging gives an ordinary person the ability to have a conversation with a wide audience and has become one of the fastest growing uses of the Web. However, dozens of employee-bloggers have been terminated for exercising what they consider to be their First Amendment right to free speech and would-be consumer advocates face potential liability for voicing their opinions. To avoid identification and prevent retribution, bloggers have sought to maintain anonymity by taking advantage of various tools and procedures - anti-forensics. Unfortunately some anonymous bloggers also post content that is in violation of one or more laws. Some blogging content might be viewed as harassing others - an area known as cyber-bullying. Law enforcement and network forensics specialists are developing procedures called Counter Anti-forensics that show some promise to identify those who violate the law. However, these techniques must be used with caution so as not to violate the rights of others