Two New Statistics to Detect Answer Copying

Two new indices to detect answer copying on a multiple-choice test—S₁ and S₂—were proposed. The S₁ index is similar to the K index (Holland, 1996) and the K₂ index (Sotaridona & Meijer, 2002) but the distribution of the number of matching incorrect answers of the source and the copier is modeled by the Poisson distribution instead of the binomial distribution to improve the detection rate of K and K₂. The S₂ index was proposed to overcome a limitation of the K and K₂ index, namely, their insensitiveness to correct answers copying. The S₂ index incorporates the matching correct answers in addition to the matching incorrect answers. A simulation study was conducted to investigate the usefulness of S₁ and S₂ for 40- and 80-item tests, 100 and 500 sample sizes, and 10%, 20%, 30%, and 40% answer copying. The Type I errors and detection rates of S₁ and S₂ were compared with those of the K₂ and the ω copying index (Wollack, 1997). Results showed that all four indices were able to maintain their Type I errors, with S₁ and K₂ being slightly conservative compared to S₂ and ω. Furthermore, S₁ had higher detection rates than K₂. The S₂ index showed a significant improvement in detection rate compared to K and K₂.     

Comparison of Answer Copying Indices with Real Data

This study investigated the Type I error rate and power of four copying indices, K-index (Holland, 1996), Scrutiny! (Assessment Systems Corporation, 1993), g₂ (Frary, Tideman, & Watts, 1977), and ω (Wollack, 1997) using real test data from 20,000 examinees over a 2-year period. The data were divided into three different test lengths (20, 40, and 80 items) and nine different sample sizes (ranging from 50 to 20,000). Four different amounts of answer copying were simulated (10%, 20%, 30%, and 40% of the items) within each condition. The ω index demonstrated the best Type I error control and power in all conditions and at all α levels. Scrutiny! and the K-index were uniformly conservative, and both had poor power to detect true copiers at the small α levels typically used in answer copying detection, whereas g₂ was generally too liberal, particularly at small α levels. Some comments on the proper uses of copying indices are provided.     

The Use of Hierarchical Generalized Linear Model for Item Dimensionality Assessment

To assess item dimensionality, the following two approaches are described and compared: hierarchical generalized linear model (HGLM) and multidimensional item response theory (MIRT) model. Two generating models are used to simulate dichotomous responses to a 17-item test: the unidimensional and compensatory two-dimensional (C2D) models. For C2D data, seven items are modeled to load on the first and second factors, θ₁ and θ₂, with the remaining 10 items modeled unidimensionally emulating a mathematics test with seven items requiring an additional reading ability dimension. For both types of generated data, the multidimensionality of item responses is investigated using HGLM and MIRT. Comparison of HGLM and MIRT's results are possible through a transformation of items' difficulty estimates into probabilities of a correct response for a hypothetical examinee at the mean on θ and θ₂. HGLM and MIRT performed similarly. The benefits of HGLM for item dimensionality analyses are discussed.     

CAN A TEST BE TOO RELIABLE?

It is shown that summary statistics that are commonly used to measure test quality (reliability, mean r _bis, and mean proportion correct) can be seriously misleading. This is demonstrated and explained.     

The Quechua Manta Pouch: A Caretaking Practice for Buffering the Peruvian Infant Against the Multiple Stressors of High Altitude

The manta pouch—a caretaking practice of tightly swaddling and enclosing the infant in a set of cloths and blankets—and other caretaking practices are described for high-altitude resident (>4,000 m) Quechua mother-infant pairs ( N = 14). The manta pouch modifies the microenvironment inside the pouch so that, compared to the ambient environment, the temperature is higher and more stable, the humidity is higher, the partial pressure of O₂ is lower, and stimulation levels are reduced. As the infant gets older, the characteristics of the pouch are modified such that the infant is increasingly exposed to ambient conditions. These caretaking practices may benefit the infant by buffering the infant from the multiple ecological stressors of high altitude, but they may also incur costs by exposing the infant to additional microenvironmental stressors (e.g., higher CO₂ levels) and by reducing stimulation and limiting infant movement.     

Multidimensionality and IRT-Based Item lnvariance Indexes: The Effect of Between-Group Variation in Trait Correlation

Using a bidimensional two-parameter logistic model, the authors generated data for two groups on a 40-item test. The item parameters were the same for the two groups, but the correlation between the two traits varied between groups. The difference in the trait correlation was directly related to the number of items judged not to be invariant using traditional unidimensional IRT-based unsigned item invariance indexes; the higher trait correlation leads to higher discrimination parameter estimates when a unidimensional IRT model is fit to the multidimensional data. In the most extreme case, when r_{θ1 θ2}= Ofor one group and r _{θ1 θ2}= 1.0 for the other group, 33 out of 40 items were identified as not invariant. When using signed indexes, the effect was much smaller. The authors, therefore, suggest a cautious use of IRT-based item invariance indexes when data are potentially multidimensional and groups may vary in the strength of the correlations among traits.     

Maraschino Cherry: A Laboratory-Lecture Unit

ABSTRACT:  Oregon State Univ. has offered FST 102 "Maraschino Cherry" as a 1-credit orientation course since 1994. The maraschino cherry serves as a vehicle from which faculty give their disciplinary perspective, for example, the chemistry of the maraschino cherry, processing unit operations, microbiology and food safety, food law, sensory analysis, product development, and so on. This laboratory-lecture unit was developed to provide reference background information, including instructions for making maraschino cherries. The unit explains the functions of SO₂, CaCl₂, acidulants (citric or HCl), and sodium chlorite in cherry brine formulations, as well as the critical role of pH in cherry brine formulation and processing of maraschino cherries. How to estimate °Brix of sugar syrups by the Pearson square method is described. The unit gives students an understanding of the regulatory distinctions between certified colorants and colorants exempt from certification; artificial, natural, and with other natural flavors (WONF) flavorings; and additives and ingredients. A brief historical perspective of maraschino cherries is given. Study questions and suggested student projects are included.     

金口河区空气中PM2.5和PM10的变化趋势及防治措施

由PM_2.5和PM₁₀引起的区域性大气污染日趋严重,对环境安全、动植物和人体健康造成了严重危害。本文通过对金口河区三年内新增企业情况、主要原辅料年用量及产品硅的年产生量、固体颗粒物年产生量与年排放量及空气中PM_2.5和PM10含量的监测数据统计分析,评价出PM_2.5和PM₁₀的污染状况,进而提出可行的对策与建议。     

An Ordinal Pattern Analysis of Four Hypotheses Describing the Interactions between Drug-addicted, Chronically Disadvantaged, and Middle-Class Mother-Infant Dyads

This study investigated mother-infant interactions in 18 dyads. All participants were African American and enrolled in an early intervention program because the infants (2–26 months of age) had developmental disabilities or were at high risk for developmental disability. Some mothers had used drugs during their pregnancy, and all mothers were of low or middle socioeconomic status. Dyads were videotaped interacting at 4 different times, separated by at least 5 months in time. Videotapes were rated in terms of infant involvement and maternal responsivity in the interaction. 4 hypotheses concerning the pattern of maternal interaction across time were tested using ordinal pattern analysis. The hypothesis that mothers would become less responsive to infants over time (H_D) as a function of drug addiction, poverty, or serious developmental delay was supported for only 4 of the 18 dyads. There was support for the hypothesis (H_j) that mothers naturally increase their responsivity over time ( N = 6) and support for the hypothesis (H_T) that mothers' interactive sensitivity fluctuates in relation to infants' involvement in the interaction over time ( N = 7). Ordinal pattern analysis has advantages in determining how well competing hypotheses describe individuals within populations relative to approaches that identify differences that apply to entire populations.     

利用煤炭固体废物制备微晶玻璃

采用50%以上的煤矸石与粉煤灰废弃物为主要原料,并添加少量的CaO、A l2O3、SiO2、MgO、K2O、Na2O等矿物原料,以CaF2/TiO2为晶核剂,经过1 400~1 500℃熔制、水淬和晶化热处理等过程制备出CaO-A l2O3-SiO2系微晶玻璃。首先对微晶玻璃的CaO、A l2O3、SiO2等成分进行优化设计,用TDA研究核化温度、核化时间、晶化温度、晶化时间及升温速率等热处理工艺参数的影响,采用SEM和XRD分析微晶玻璃的形貌与晶相结构,并检测其密度、吸水率、抗折强度、显微硬度、耐腐蚀性等物理力学性能。所制备的40%SiO2-15%A l2O3-30%CaO(质量百分数)微晶玻璃以黄长石为主晶相,晶粒度约4μm,具有优异的物理力学性能,在建筑材料领域有良好的应用前景。     

The Relationship Between Item Parameters and Item Fit

The effect of item parameters (discrimination, difficulty, and level of guessing) on the item-fit statistic was investigated using simulated dichotomous data. Nine tests were simulated using 1,000 persons, 50 items, three levels of item discrimination, three levels of item difficulty, and three levels of guessing. The item fit was estimated using two fit statistics: the likelihood ratio statistic (X²_B), and the standardized residuals (SRs). All the item parameters were simulated to be normally distributed. Results showed that the levels of item discrimination and guessing affected the item-fit values. As the level of item discrimination or guessing increased, item-fit values increased and more items misfit the model. The level of item difficulty did not affect the item-fit statistic.     

铯蒸气中产生的1（a）~3Σ_u~＋→2~3∏_g（0_g~（＋,-）,1_g,2_g）扩散带

分析了在采用高分辨的多通道光谱仪AvaSpec-2048FT对铯分子蒸汽吸收光谱进行测量时观测到了奇特的扩散带吸收谱线,中心在706.6 nm、713.2 nm和719.0 nm,对应铯分子1（a）~3Σ_u~＋→2~3∏_g（0_g~（＋,-）,1_g,2_g）三重态的跃迁,并对扩散带吸收系数随温度的变化进行了讨论。     

语用关产与跨文化交际中的五类语用失误

以语用关联假设为框架，讲座了语用语言关联，语用社会关联，语用个 体关联，语用认知关联，语用文化闻联等五种语用失误。     

Improving Person-Fit Assessment by Correcting the Ability Estimate and Its Reference Distribution

The standardized log-likelihood of a response vector (l_z) is a popular IRT-based person-fit test statistic for identifying model-misfitting response patterns. Traditional use of l_z is overly conservative in detecting aberrance due to its incorrect assumption regarding its theoretical null distribution. This study proposes a method for improving the accuracy of person-fit analysis using l_z which takes into account test unreliability when estimating the ability and constructs the distribution for each l_z through resampling methods. The Type I error and power (or detection rate) of the proposed method were examined at different test lengths, ability levels, and nominal α levels along with other methods, and power to detect three types of aberrance—cheating, lack of motivation, and speeding—was considered. Results indicate that the proposed method is a viable and promising approach. It has Type I error rates close to the nominal value for most ability levels and reasonably good power.     

语法、语用意识和能力的性别差异及其与学习动机的关系

通过调查问卷的研究方法,调查了非英语专业166名男生和206名女生在语法、语用意识／能力及其与学习动机方面的差异,以此探讨他们的语法、语用意识／能力与学习动机的关系发现：男生的语用能力、个人发展动机和信息媒介动机显著低于女生;男生的成绩动机与语法意识、语法能力、语用意识显著负相关,其情境动机与语用意识显著负相关;女生的成绩动机与语法意识、语法能力显著负相关,社会责任动机与语用意识、语用能力显著相关,个人发展动机、信息媒介动机与语用能力则显著相关。     

现代汉语形容词重叠的形式特征

与他类实词相比，形容词重叠在形式上的突出特点是：重叠类型繁多、整体格式丰富、同一基式多样。重叠类型繁多主要与形容词基式的类别有关，性质形容词和状态形容词分别有它们独有的重叠格式，如AABB、BABA、BAA等格式，也有它们共有的重叠格式ABB式。整体格式丰富可以从词的构成、词的色彩等多角度考察，格式丰富的原因主要与词语义的对称性，句法的多功能性以及及语用的描写性有关。同一基式丰富指的是同一基式可以有多种重叠格式。     

Restricting a Familiar Name in Response to Learning a New One: Evidence for the Mutual Exclusivity Bias in Young Two-Year-Olds

Children under 2¹/₂ years old tend to interpret novel words in accordance with the Mutual Exclusivity Principle, but tend not to reinterpret familiar words this way. Because alternative principle have been proposed that only predict the novel word effects, and because tests of the familiar word effects may have been flawed, a new test was administered. In Experiment 1 ( N = 32), 24- to 25-month-olds heard stories in which a novel noun was used for an atypical exemplar of a familiar noun. When asked to select exemplars of the familiar noun, they showed a small but reliable tendency to avoid the object from the story. In Experiment 2 ( N = 16), the novel nouns in the stories were replaced by pronouns and proper names, and the children did not avoid the story object in the test of the familiar noun. Thus, the aversion to this object that was observed in Experiment I was not due to its greater exposure or its being referenced immediately before testing, but to toddlers' Mutual Exclusivity bias. Their bias is hypothesized to be a form of implicit probabilistic knowledge that derives from the competitive nature of category retrieval.     

函子范畴的Incidence代数的两个例子

以箭图Q₁,Q₂,Q₃为例,构造有限偏序k范畴Γ₁,Γ₂,考虑Γ₁,Γ₂及函子范畴Γ₁^Γ2诱导的incidence代数的两个例子。     

Using an Approximate Chi-Square Statistic to Test the Number of Dimensions Underlying the Responses to a Set of Items

An approximate χ² statistic based on McDonald's (1967) nonlinear factor analytic representation of item response theory was proposed and investigated with simulated data. The results were compared with Stout's T statistic (Nandakumar & Stout, 1993; Stout, 1987). Unidimensional and two-dimensional item response data were simulated under varying levels of sample size, test length, test reliability, and dimension dominance. The approximate χ² statistic had good control over Type I errors when unidimensional data were generated and displayed very good power in identifying the two-dimensional data. The performance of the approximate χ² was at least as good as Stout's T statistic in all conditions and was better than Stout's T statistic with smaller sample sizes and shorter tests. Further implications regarding the potential use of nonlinear factor analysis and the approximate χ² in addressing current measurement issues are discussed.