Detecting Differential Item Discrimination (DID) and the Consequences of Ignoring DID in Multilevel Item Response Models

Cross‐level invariance in a multilevel item response model can be investigated by testing whether the within‐level item discriminations are equal to the between‐level item discriminations. Testing the cross‐level invariance assumption is important to understand constructs in multilevel data. However, in most multilevel item response model applications, the cross‐level invariance is assumed without testing of the cross‐level invariance assumption. In this study, the detection methods of differential item discrimination (DID) over levels and the consequences of ignoring DID are illustrated and discussed with the use of multilevel item response models. Simulation results showed that the likelihood ratio test (LRT) performed well in detecting global DID at the test level when some portion of the items exhibited DID. At the item level, the Akaike information criterion (AIC), the sample‐size adjusted Bayesian information criterion (saBIC), LRT, and Wald test showed a satisfactory rejection rate (>.8) when some portion of the items exhibited DID and the items had lower intraclass correlations (or higher DID magnitudes). When DID was ignored, the accuracy of the item discrimination estimates and standard errors was mainly problematic. Implications of the findings and limitations are discussed.     

The art of self-concretization as a necropolitical embodiment: The self-immolation of Chun Tae-il

This essay examines Chun Tae-il's self-immolation as an exemplar that showcases how a life deprived of public appearance can enter the public sphere through the willful destruction of one's body. Far from being a strange and curious deviation, self-immolation, I argue, is a necropolitical form of public embodiment for those who have been marginalized and excluded from the space of appearance. Chun Tae-il's self-immolation illustrates that there is an alternative form of self-suspension practiced by subaltern subjects: the art of self-concretization. While all subjects of publicity are required to bracket their self-interests when entering the public realm, Chun Tae-il's self-immolation indicates that the entrance fee for minoritized subjects can be life itself, thus epitomizing the limit condition of self-purgation in the public realm.     

Exploring the relationships between students' academic motivation and social ability in online learning environments

This research explicates the construct of social ability and describes the relationship between students' academic motivation and social ability in online learning environments. Findings reveal perceived peers social presence, perceived written communication skills, perceived instructor social presence, comfort with sharing personal information, and social navigation as the five factors that define social ability. In addition, the multivariate multiple regression analyses indicate that different motivational constructs vary in their relationships with the multiple social ability factors. Intrinsic goal orientation is related to perceived peers social presence. Self-efficacy explains the variance of perceived instructor social presence and comfort with sharing personal information. Task value is associated with social navigation and both perceived peers and instructor social presence. Additional studies are needed to replicate the current findings and further explicate social ability in online learning, to continue to improve the social ability instrument, and to examine the value of other academic motivation beliefs in predicting social ability as well as that of social ability in predicting learning outcomes.     

Lysozyme refolding at high concentration by dilution and size-exclusion chromatography

This study of renaturation by dilution and size exclusion chromatography (SEC) addition of urea to improve yield as well as the initial and final protein concentrations showed that although urea decreased the rate of lysozyme refolding, it could suppress protein aggregation to sustain the pathway of correct refolding at high protein concentration; and that there existed an optimum urea concentration in renaturation buffer. Under the above conditions, lysozyme was successfully refolded from initial concentration of up to 40 mg/mL by dilution and 100 mg/mL by SEC, with the yield of the former being more than 40% and that of the latter being 34.8%. Especially, under the condition of 30 min interval time, i.e. τ>2(t _R2−t_R1), the efficiency was increased by 25% and the renaturation buffer could be recycled for SEC refolding in continuous operation of downstream process. Project supported by Zhejiang Provincial Natural Science Foundation of China (No. 201099) and the Local-Lab Project by Korean Institute of Science and Technology Evaluation and Planning, Korea     

Analyzing Medical Students' Definitions of Sex

An inaccurate definition of what constitutes sex can negatively impact the sexual health and wellbeing of patients. This study aimed to determine which behaviors medical students consider to be sex. Survey questions about various sexual behaviors were administered to medical students. All participants agreed that penile-vaginal penetration is sex. More than 25% of participants did not consider genital-genital contact without penetration, oral-genital contact, foreign object in rectum, and forced vaginal/rectal penetration as sex. Nonheterosexuals were more likely to consider genital-genital contact without penetration sex. We determined there was less than complete consensus among future physicians on what activities are considered sex.     

UNDERSTANDING TEST‐TYPE ASSIGNMENT: WHY DO SPECIAL EDUCATORS MAKE UNEXPECTED TEST‐TYPE ASSIGNMENTS?

We interviewed special educators (a) whose students with disabilities (SWDs) were proficient on the 2008 general education assessment but were assigned to the 2009 alternate assessment based on modified achievement standards (AA‐MAS), and (b) whose students with mild disabilities took the 2008 alternate assessment based on alternate achievement standards (AA‐AAS) and then the 2009 AA‐MAS. We explored teachers’ rationales for test‐type assignment, student characteristics, and quality of instruction to determine the test‐type decisions’ appropriateness. All teachers based their decisions on combinations of factors in the guidelines plus subjective and noninstructional factors. Findings raised concerns about the subjectivity of the assessment assignment system and the inappropriate grade‐level instruction for SWDs. Future research, implications of these findings, and limitations are discussed.     

Do reductions in class size raise students’ test scores? Evidence from population variation in Minnesota's elementary schools

Many U.S. states and cities spend substantial funds to reduce class size, especially in elementary (primary) school. Estimating the impact of class size on learning is complicated, since children in small and large classes differ in many observed and unobserved ways. This paper uses a method of Hoxby (2000) to assess the impact of class size on the test scores of grade 3 and 5 students in Minnesota. The method exploits random variation in class size due to random variation in births in school and district catchment areas. The results show that reducing class size increases mathematics and reading test scores in Minnesota. Yet these impacts are very small; a decrease of ten students would increase test scores by only 0.04–0.05 standard deviations (of the distribution of test scores). Thus class size reductions are unlikely to lead to sizeable increases in student learning.     

The effects of job demands,job resources,and personal resources on the psychological well-being of middle-aged workers in the United States: assessing latent profile differences

International Journal for Educational and Vocational Guidance - The purpose of this study is to better understand the psychological well-being of aged workers in the job demands-resources model. We...     

Confronting dictatorship,democratization, and post‐democratization – personal reflection on intellectual and social practices in the context of dictatorship,democratization and post‐democratization

Abstract

This essay tries to trace the life trajectory of an intellectual, in terms of his intellectual and social practices, who wants to live through modern Korean history via progressive activism. The trajectory can be divided into three different stages: the first comes with the military developmental dictatorship in 1961, ending in 1987. The next is during the democratic transition since the Democratic Uprising in June 1987, which put the Korean society onto the road of democratization. The last one should be the so‐called ‘post‐democratization’ period in which we now find ourselves. This is more a story than an analysis of the progressive intellectual movement in the form of the personal recollections. The story is, however, not just about an individual but it is a window giving a glimpse into the larger trajectory that many progressive intellectuals have gone through, and that directly reflects the huge changes in contemporary history of South Korea, such as the interaction between the domination and social movements.