This article reviews the use of the software program lp_solve version 5.5 for solving mixed-integer automated test assembly (ATA) problems. The program is freely available under Lesser General Public License 2 (LGPL2). It can be called from the statistical language R using the lpSolveAPI interface. Three empirical problems are presented to demonstrate how to use the program and interface to (a) simultaneously assemble multiple test forms with absolute targets for their test information functions, (b) assemble shadow tests for computerized adaptive testing, and (c) assemble multistage tests using relative targets for their test information functions, all subject to various quantitative and categorical constraints. The results of this study indicate that it is now possible for researchers and testing organizations to implement ATA for small to moderately sized test assembly problems using free software.Keywords automated test assembly, lp_solve, mixed-integer programming, MIP solver, RThe discovery of the natural applicability of mixed-integer programming (MIP) to automated test assembly (ATA) has led to an increasing amount of research on the topic. One major part of the research has focused on how to formalize test-assembly problems, such as MIP problems, with objectives and constraints. A comprehensive review of all the test specifications that can currently be modeled as objectives or constraints is given in van der Linden (2005).Another important part of ATA is transferring the MIP formulation of the problem to software programs (generally known as ''solvers'') that solve the problem for an optimal solution. Many different solvers are available, including extremely powerful solvers in commercial software, such as OPL-CPLEX 6.3 and CPLEX 12.1 (both from IBM ILOG), LINGO 12.0 (LINDO), and the Premium Solver Platform 7.0 add-in for Microsoft Excel. The prices of these solvers range from hundreds to thousands of dollars for full editions. Academic licenses are much more affordable, but are only available for research in university settings.It is not widely known in the testing community that some attractive solvers for ATA problems are available as freeware. One of the best, lp_solve version 5.5, can be accessed through the Computer Software Review statistical software R, which is also available for free. This article reviews the use of this software for solving ATA problems.Using the real data presented in Cor, Alves, and Gierl (2008), three typical ATA problems were formulated and implemented to evaluate the performance of lp_solve 5.5. The first of these was the simultaneous assembly of multiple forms with absolute test information function (TIF) targets. The second involved assembly of shadow tests in computerized adaptive tests CAT. The third problem involved assembly of multistage tests with relative TIF targets.The goal of this review is to make ATA more accessible for smaller (nonprofit) organizations that neither qualify for academic licenses for commercial solvers nor can afford full licenses.Program Des...

Inflammation and oxidative stress serve interrelated roles in the development of atherosclerosis and other vascular diseases. Quercetin has been previously reported to exhibit numerous beneficial properties towards several metabolic conditions and cardiovascular disease. The present study aimed to evaluate the effects of quercetin on the 5'adenosine monophosphate-activated protein kinase (AMPK)/sirtuin 1 (SIRT1)/NF-κB signaling pathway and inflammatory/oxidative stress response in diabetic-induced atherosclerosis in the carotid artery of rats. Male Wistar rats were used to create a diabetes-induced atherosclerosis model by the administration of high fat diet (HFD) with streptozotocin, which lasted for 8 weeks. Control and diabetic rats received quercetin (30 mg/kg/day; orally) for the last 2 weeks of the diabetic period. Plasma lipid profile and vascular levels of oxidative stress markers, inflammatory cytokines, NF-κB signaling proteins and SIRT1 expression were evaluated using ELISA and western blotting. Quercetin treatment in HFD diabetic rats was reported to improve the lipid profile and reduce the number of atherosclerotic lesions, atherogenic index and malondialdehyde levels, whilst increasing the activity of enzymatic antioxidants in the carotid artery. Additionally, the inflammatory response was suppressed by quercetin administration, as indicated by the reduced NF-κB and IL-1β levels, and increased IL-10 levels. Furthermore, SIRT1 expression was revealed to be significantly increased in response to quercetin treatment compared with non-treated HFD rats. However, these effects of quercetin were abolished or reversed by the administration of compound-C (0.2 mg/kg), a specific AMPK blocker, in HFD rats. Therefore, quercetin may have promising potential in ameliorating atherosclerotic pathophysiology in the rat carotid artery by inhibiting oxidative stress and inflammatory responses mechanistically by modulating the AMPK/SIRT1/NF-κB signaling pathway.

Variable-length computerized adaptive testing (VL-CAT) allows both items and test length to be “tailored” to examinees, thereby achieving the measurement goal (e.g., scoring precision or classification) with as few items as possible. Several popular test termination rules depend on the standard error of the ability estimate, which in turn depends on the item parameter values. However, items are chosen on the basis of their parameter estimates, and capitalization on chance may occur. In this article, the authors investigated the effects of capitalization on chance on test length and classification accuracy in several VL-CAT simulations. The results confirm that capitalization on chance occurs in VL-CAT and has complex effects on test length, ability estimation, and classification accuracy. These results have important implications for the design and implementation of VL-CATs.

This study compared four item-selection procedures developed for use with severely constrained computerized adaptive tests (CATs). Severely constrained CATs refer to those adaptive tests that seek to meet a complex set of constraints that are often not conclusive to each other (i.e., an item may contribute to the satisfaction of several constraints at the same time). The procedures examined in the study included the weighted deviation model (WDM), the weighted penalty model (WPM), the maximum priority index (MPI), and the shadow test approach (STA). In addition, two modified versions of the MPI procedure were introduced to deal with an edge case condition that results in the item selection procedure becoming dysfunctional during a test. The results suggest that the STA worked best among all candidate methods in terms of measurement accuracy and constraint management. For the other three heuristic approaches, they did not differ significantly in measurement accuracy and constraint management at the lower bound level. However, the WPM method appears to perform considerably better in overall constraint management than either the WDM or MPI method. Limitations and future research directions were also discussed.

In psychological and survey research, the prevalence and serious consequences of careless responses from unmotivated participants are well known. In this study, we propose to iteratively detect careless responders and cleanse the data by removing their responses. The careless responders are detected using person-fit statistics. In two simulation studies, the iterative procedure leads to nearly perfect power in detecting extremely careless responders and much higher power than the noniterative procedure in detecting moderately careless responders. Meanwhile, the false-positive error rate is close to the nominal level. In addition, item parameter estimation is much improved by iteratively cleansing the calibration sample. The bias in item discrimination and location parameter estimates is substantially reduced. The standard error estimates, which are spuriously small in the presence of careless responses, are corrected by the iterative cleansing procedure. An empirical example is also presented to illustrate the proposed procedure. These results suggest that the proposed procedure is a promising way to improve item parameter estimation for tests of 20 items or longer when data are contaminated by careless responses.