水稻产量影响的主成分分析

利用主成分分析法和回归分析法分析影响水稻区试品种产量的因子,结果表明,影响产量的主成分因子分别是热量、海拔—雨量、穗重和粒数;利用各因子作为自变量,水稻产量作为因变量,进行逐步回归分析,建立一个产量回归方程。方程的相关系数(R)达0.99983,各因子对生产量影响的大小为纬度>有效穗>实粒数>千粒重>年均降雨量。     

关于偏相关系数的计算公式的一点注记

首先对偏相关系数的常用的定义与计算方法作了归纳,然后从多元正态分布理论中的条件分布的结论出发,推导得出通过相关系数阵或协方差阵求逆的方法来计算偏相关系数的公式,从而对利用相关系数阵求逆方法计算偏相关系数的公式给出了合理的解释。     

基于灰色关联度分析法对农用地分等因素的评价--以内蒙古乌拉特中旗为例

笔者应用灰色关联度分析法对乌拉特中旗农用地分等因素进行评价,以各乡镇为评价单元,选取作物的平均产量作为评价的参考数列,计算各因素与作物产量的关联系数,从而进一步得到它们的关联程度,由此得出影响乌拉特中旗农用地生产力水平的主要因素,分别为有机质和坡度;其次为土壤侵蚀程度和距障碍层深度;有效土层厚度、灌溉保证率和表层质地同等程度地影响着研究区的作物产量,较前面4个因素影响程度小。该结果为本旗以后农用地分等分等因素的选取提供参考依据,同时也为当地居民在以后的生产活动中因地制宜,不断改善和提高限制作物生产的因素提供依据。     

学校信息化应用的影响因素研究

学校信息化应用受到多种因素的影响。文章阐述了学校信息化的四种具体应用,指出影响学校信息化应用的因素,具体包括三个基础因素和一个保障因素,通过实证数据统计分析,利用相关分析法对学校信息化应用影响因素与学校信息化应用之间的关系进行分析。     

磁性化肥养分效应磁效应及其相互关系的研究

本文采用二因素随机区组试验,探讨了不同NPK养分,不同磁化处理的磁性化肥对杂交水稻产量及产量构成因素的影响。统计结果表明:不同磁肥对水稻产量的影响差异达到了极显著水平,其中以N_3P_1K_1×磁化粉煤灰(2000GS磁化处理)的磁肥的效果最好。养分与磁处理间存在显著互作反应,不同磁肥对有效穗数,每穗实粒数的影响均极显著,但对千粒重的影响不显著,水稻产量与有效穗数的偏相关程度较大,水稻产量约70％可由每株有效穗数、每穗实粒数的变异决定,NPK养分是磁肥主成分,其效应大于磁效应,且磁效应与养分有关。     

贵州烤烟化学成分的因子分析

本文对我国优质烤烟产区贵州省的烤烟化学成分进行因子分析.化学成分相关系数矩阵表明,烤烟多种化学成分间存在显著或极显著的相关性,相关系数矩阵前四个特征根的累计贡献率已达88.309%.由化学成分的因子载荷矩阵得到四个主因子.     

全微分在偏微分方程变量替换中的应用

提供了一种用求多元函数全微分的方法,解决了多元偏微分方程的变量替换问题,它比其它的方法更具系统性和完整性.     

Modeling Configural Patterns in Latent Variable Profiles: Association With an Endogenous Variable

A model is proposed for identifying latent predictor score patterns associated with a latent outcome variable. The model employs 2 new devices: (a) a path coefficient vector of contrast coefficients to describe a configural pattern in a structural model, and (b) a new type of latent variable with values that quantify the match of the person's latent predictor variable profile pattern to a theoretical pattern associated with the factor. The model is illustrated using data on perceptions and evaluations of political candidates during a debate. Findings suggest a pattern of scores on the perceptual variables associated with perceived debate success for female observers but not for male observers.     

季节变动时间序列的两种新预测模型

对于季节变动时间序列提出了一种新的乘法分解模型，它可表示成年度变动因子、季节变动因子、总平均值和随机变动因子的乘积．然后在此基础上给出渐进预测模型和乘法预测模型，最后进行了实例分析．     

Testing Complex Correlational Hypotheses With Structural Equation Models

It is often of interest to estimate partial or semipartial correlation coefficients as indexes of the linear association between 2 variables after partialing one or both for the influence of covariates. Squaring these coefficients expresses the proportion of variance in 1 variable explained by the other variable after controlling for covariates. Methods exist for testing hypotheses about the equality of these coefficients across 2 or more groups, but they are difficult to conduct by hand, prone to error, and limited to simple cases. A unified framework is provided for estimating bivariate, partial, and semipartial correlation coefficients using structural equation modeling (SEM). Within the SEM framework, it is straightforward to test hypotheses of the equality of various correlation coefficients with any number of covariates across multiple groups. LISREL syntax is provided, along with 4 examples.     

基于概率统计的冷冲模冲裁力计算建模

冲压过程中材料会经历比较大的弹塑性变形,在工具与工艺设计中最常考虑的影响因素即为材料力学性能。尽管通过传统弹塑性理论可能从理论上得到包括诸多因素在内的设计分式,但是这些因素往往体现出随机性,需要获取相关系数对理论公式进行修正,所以难免存在一些不足。本文就针对冲裁模的设计建立部分概率模型。     

Two-Step Approach to Partial Factorial Invariance: Selecting a Reference Variable and Identifying the Source of Noninvariance

To date, no effective empirical method has been available to identify a truly invariant reference variable (RV) in testing measurement invariance under a multiple-group confirmatory factor analysis. This study proposes a method that, in selecting an RV, uses the smallest modification index (min-mod). The method’s performance is evaluated using 2 models: (a) a full invariance model, and (b) a partial invariance model. Results indicate that for both models the min-mod successfully identifies a truly invariant RV (Study 1). In Study 2, we use the RV found in Study 1 to further evaluate the performance of item-by-item Wald tests at locating a noninvariant variable. The results indicate that Wald tests overall performed better with an RV selected in a partial invariance model than an RV selected in a full invariance model, although in certain conditions their performances were rather similar. Implications and limitations of the study are also discussed.     

“翻转课堂”模式下学生课堂学习参与度量表编制

学生课堂学习参与度是教学效果的决定性因素。经文献分析,"翻转课堂"模式下学生课堂学习参与度涉及注意力集中度、师生互动、生生互动、课堂兴趣度、批判性思维和课堂满意度六个维度。经检验,以此为基础开发的量表的总Cronbach's Alpha系数为0.88,各特定条目与其他条目汇总的Pearson相关系数和剔除某一条目后的Cronbach's Alpha系数结果良好,探索性因子分析中累积贡献方差率为66.29%,特征值≥1的公因子有6个,与设计量表前得出的评估指标相吻合,验证性因子分子中参与度理论模型与数据拟合结果良好。结果表明:此量表具有很好的信度和效度,能够较为科学地检测"翻转课堂"模式下学生课堂学习的参与程度。     

大学生英、日语言学习迁移中的影响因素和因素结构分析

以210名大学生为对象开展问卷调查,并据此进行因素分析,抽取作为第二外语学习的日语学习过程中影响学习迁移的主要因素,将9个主因素之间的相关通过AMOS4．0做结构模型,验证从英语学习到日语学习的学习迁移过程中9因素之间的相关,并根据相关系数具体分析各因素之间相关得出的结论。     

Evaluation of Dimensionality in the Assessment of Internal Consistency Reliability: Coefficient Alpha and Omega Coefficients

In the lead article, Davenport, Davison, Liou, & Love demonstrate the relationship among homogeneity, internal consistency, and coefficient alpha, and also distinguish among them. These distinctions are important because too often coefficient alpha—a reliability coefficient—is interpreted as an index of homogeneity or internal consistency. We argue that factor analysis should be conducted before calculating internal consistency estimates of reliability. If factor analysis indicates the assumptions underlying coefficient alpha are met, then it can be reported as a reliability coefficient. However, to the extent that items are multidimensional, alternative internal consistency reliability coefficients should be computed based on the parameter estimates of the factor model. Assuming a bifactor model evidenced good fit, and the measure was designed to assess a single construct, omega hierarchical—the proportion of variance of the total scores due to the general factor—should be presented. Omega—the proportion of variance of the total scores due to all factors—also should be reported in that it represents a more traditional view of reliability, although it is computed within a factor analytic framework. By presenting both these coefficients and potentially other omega coefficients, the reliability results are less likely to be misinterpreted.     

基于“做中学”理念下学习效果相关因子的分析研究——以大学生的课堂学习为例

"做中学"理念下的课堂,对于现代教师与大学生都是一次新的尝试与挑战。文章对学习效果与教学三要素进行相关性分析,对出现的两大现象(相关系数的比较中,教师因子大于学生因子;认知因素方面,认知策略因子大于认知知识)进行原因分析,并根据"做中学"课堂需注意的问题提出相应的建议。     

The factor invariance of student ratings of instruction under three sets of directions

This research addressed itself to the issue of the validity of student ratings of instruction, describing and comparing the factor patterns obtained under three different sets of directions. Graduate education students (n=414) were randomly assigned to one of three conditions: administrator use, instructor use, and student use. Subjects in each condition received a different cover letter which explained the purported use to which their ratings were to be put and which asked them to rate their course and instructor on a 33-item rating scale. Data were factor analyzed using principal-axes factor method followed by an oblique transformation. The factor patterns obtained were then compared using the coefficient of congruence. While two clusters (organization/structure and rapport/interaction) emerged across all three conditions, a third cluster appeared which was unique to each condition. The coefficients of congruence obtained generally indicated that the factors could not be considered invariant across the three conditions.     

Factors influencing the demand for higher education: The case of Cyprus

The proportion of young people opting for third level education in Cyprus is exceptionally high, currently about 60% of the relevant age group. This has caused concern among the country's policy makers who are aware of the limited capacity of the Cyprus economy to accommodate the increasing supply of higher education graduates. In the present study, an attempt is made to identify and examine the factors influencing young Cypriots to select higher education over direct employment at the end of their secondary education. A survey was conducted among 811 final form secondary school students in Cyprus in the academic year 1993/1994. Through factor analysis, seven factors with a potential effect on the students' educational and occupational intentions were identified. They were the following: Psychological/Individual, Occupational I, Occupational II, Economic, Consumption, Secondary School Subjects, and Significant Others. These factors, along with a number of student background characteristics (gender, socioeconomic status, ability, and secondary school specialisation) were used as explanatory variables in a logistic regression model with the student's educational intentions serving as the dependent variable. The psychological/individual factor, the second occupational factor, and secondary school specialisation were shown to have a significant effect on the intention to pursue third level education. The paper points to the importance of analysing and examining student characteristics and motivational patterns in the effort to understand, and, if possible, influence trends in the demand for higher education.     

Resistance partial factor and reliability of cast ball-and-socket support joint

Considering the uncertainty of material performance, geometric characteristic and analysis method, the analysis of statistical parameters of the resistance of cast ball-and-socket support joints and the reliability analysis are carried out by JC method (improved first-order second-moment method) based on the relevant experimental data. Results show that the resistance partial factor of the joint increases with the increase of the reliability index. The resistance partial factors are suggested corresponding to the reliability index under different load combinations. Moreover, the suggested resistance partial factor is adopted in reliability design, and it is found that the reliability index of the joint is larger than the target reliability index. The optimal load combination is the one in which live load plays an important control role. Finally, based on the suggested resistance partial factors, the reliability analysis of cast ball-and-socket support joints of a project is conducted.     

多元t-copula尾相依的单调性

考虑了多元t-copula的上尾象限相依指数和上尾极值相依指数,该t-copula是在相依结构下定义的．由于多元连续型随机变量的copula函数关于严格单调递增变换具有不变性质,由此推导了多元t-copula的尾相依指数的精确表达式,得到的结果明显比以往文献给出的结论更加简洁．然后,讨论了这2个相依指数关于相关系数的局部单调性质：上尾极值相依指数关于相关系数是严格单调递增的,但上尾象限相依指数的单调性比较复杂．通过蒙特卡罗模拟数据验证了结果的正确性．同时,发现所有结论可以推广到生成随机变量是正则变化的分布类中．