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排序方式: 共有283条查询结果,搜索用时 15 毫秒
1.
This study developed a composite machine learning algorithm for attribution of materials of forensic interest (like ammonium nitrate) to original sources. k-nearest neighbor and random forest models were used for source elimination and classification, respectively, in a two-step, composite algorithm based on particle color, size/shape, and trace element concentration features. Novel approaches for simulation to supplement within-source reference features based on empirically measured multi-lot analyses, an improved hold-one-lot-out method for cross-validation, an assessment of the likelihood of the presence of a reference sample, fusion of the source probabilities from the respective classification models, and the calculation of metrics for assessing ensemble sourcing performance are described. Excellent sourcing predictions were obtained; the sourcing algorithm identified the correct source as the top choice 89% of the time, and the correct source was identified to be an average of 2.7 times more likely than the most likely incorrect source. 相似文献
2.
Godfred Matthew Yaw Owusu Rita Amoah Bekoe Fred Kwasi Anokye Lydia Anyetei 《国际公共行政管理杂志》2020,43(13):1143-1155
ABSTRACT This study examines the views of students on the ethics of tax evasion, their intentions to evade tax, and investigates the factors that predict such intentions. Relying on the extended version of the Theory of Planned Behaviour, the study investigated whether attitudes, subjective norms, perceived behavioural control, and moral obligation may be good predictors of the intention to evade tax. Data were gathered from 662 students of University of Ghana Business School using questionnaires. The hypotheses were tested using the structural equation modelling technique. Results indicate that the intention to evade tax among the students is low and most respondents generally perceive tax evasion as an unethical practice. The results also demonstrate that attitude, subjective norms and moral obligations have important implications on the intention to evade tax. The evidence we provide should be useful to governments and tax agencies interested in promoting responsible tax compliance behaviour among individual taxpayers. 相似文献
3.
A plethora of literature has been undertaken to study the validity of the Feldstein–Horioka (FH) puzzle. However, divergent views continue to persist in the FH puzzle literature. This study explores the empirical validity of the FH puzzle in the case of South Asian countries using annual data from 1960 to 2017. Both panel data approach and Markov‐switching regression approach are used to empirically analyze the FH puzzle. The results of the cointegration test confirm the long‐run relationships between saving and investment in the selected South Asian countries. The results of Markov‐switching regression confirm that the saving‐retention coefficient has shifted from high to low values and also from low to high values. Thus, the FH puzzle exists for a particular time period and mostly depends on the regime shifts in the South Asian countries. The results of panel fully modified ordinary least squares (FMOLS) and dynamic ordinary least squares (DOLS) methods also confirm that FH puzzle holds for the South Asian countries. Therefore, the study suggests that any saving promotion policies are desirable for enhancing investment among the South Asian regions. 相似文献
4.
The current study analyzes police use of force as a series of time-bound transactions between officers, civilians, and bystanders. The research begins with a systematic social observation of use-of-force events recorded on police body-worn cameras in Newark, New Jersey. Researchers measure the occurrence and time stamps for numerous participant physical and verbal behaviors. Data are converted into a longitudinal panel format measuring all observed behaviors in 5-second intervals. Panel logistic regression models estimate the effect of each behavior on use of force in immediate and subsequent temporal periods. Findings indicate certain variables influence use of force at a distinct point in time, whereas others exert influence on use of force across multiple time periods. The most influential variables relate to authority maintenance theoretical constructs. This finding supports prior perspectives arguing that police use of force largely results from officer attempts to maintain constant authority over civilians during face-to-face encounters. Nonetheless, a range of additional variables reflecting procedural justice, civilian resistance, and bystander presence significantly affect when police use force during civilian encounters. Results provide nuance to theoretical frameworks considering use of force as resulting from the interplay between officer and civilian actions and reactions. 相似文献
5.
《Science & justice》2023,63(2):181-199
This study empirically demonstrates the efficacy of a two-level Dirichlet-multinomial statistical model (the Multinomial system) for computing likelihood ratios (LR) for linguistic, textual evidence with multiple stylometric feature types with discrete values. The LRs are calculated separately for each feature type, namely, word, character and part of speech N-grams (N = 1,2,3), which are combined as overall LRs through logistic regression fusion. The Multinomial system’s performance is compared with that of a previously proposed system with the cosine distance (the Cosine system) using the same data (i.e., documents collated from 2160 authors). The experimental results show that: (1) the Multinomial system outperforms the Cosine system with the fused feature types by a log-LR cost of ca. 0.01 ~ 0.05 bits; and (2) the Multinomial system is more advantageous in performance with longer documents than the Cosine system. Although the Cosine system is more robust overall against the sampling variability arising from the number of authors included in the reference and calibration databases, the Multinomial system can achieve reasonable stability in performance; for example, the standard deviation value of the log-LR cost becomes lower than 0.01 (10 random samplings of authors for the reference and calibration databases) with 60 or more authors in each database. 相似文献
6.
Obtaining citizens’ voluntary compliance with political decisions is a fundamental democratic challenge. Fair treatment by public officials plays a key role in theoretical and empirical studies on citizens’ compliance and cooperation. Yet it is unclear whether citizens within different societies react to (un)fair treatment in the same way. Using multilevel structural equation modelling and multilevel regression analysis on the European Social Survey 2010–2 (N = 52,458), this article shows that perceptions of fair treatment by police officers are associated with higher levels of trust in political institutions and in turn stronger compliant and cooperative attitudes of citizens in 27 countries. Yet the link between perceptions of unfair treatment and institutional trust is stronger in countries in which fair behaviour is more prevalent. While fair treatment is often considered to be a universal norm affecting citizens in a uniform way, this article sheds light on important cross-national variations. 相似文献
7.
Palatal suture fusion has seen little testing and/or application due in part to an inadequately described relationship to formal age ranges. This study presents a modified scoring method that examines fusion on samples of modern documented adult males and compares two Bayesian approaches to age estimation. In the first analysis, American and Portuguese collections were used to derive univariate and multivariate transition analysis (TA) parameters, which combined with an informative prior, estimated age in a sample of modern Americans and Portuguese. For the second analysis, a Bayesian multiple linear regression (BMLR) used indicator statuses as the independent variables with age as the dependent variable. Highest posterior density regions (HPDRs) and highest posterior density intervals (HDI) were calculated for a holdout sample. Final age estimates for the methods were tested for accuracy using cumulative binomial tests at 75% and 90% coverages. The HPDRs from multivariate TA captured age better for younger individuals, but consistently underaged. The cumulative binomial tests on the BMLR results indicated the prediction intervals performed as expected, and we show they are narrower (more precise) and/or more accurate than the corresponding HPDR. The modified method presented here formally links palatal suture obliteration to age using two different approaches, one of which (BMLR) is new to the aging literature. The BMLR provided results free from bias and more reasonable age ranges while maintaining accuracy. We present a look-up table and a free, simple R file for users to download and run their own estimates with BMLR. 相似文献
8.
Choice of political party is an important decision a citizen faces in a democracy. In recent times, as democracies in many countries have matured, a number of studies are focusing on party and candidate choice and their various determinants. India, being the largest democracy, provides a fertile ground for such research. Accordingly, in this paper we concentrate on demographic characteristics, newspaper-reading habits of voters, and their political choice. To study this we have considered a very unique data set collected just before the watershed elections in the state of West Bengal in India, where the ruling Communist coalition was defeated after thirty-four years of power in the state. The survey was conducted using a structured questionnaire to collect information on demographic characteristics of voters and their political choice. The respondents were asked to indicate their party choice from among the three major political parties. As the literature shows that gender, age, education, income levels, marital status, occupational status, and choice of newspaper have significant impact on political choice, we have considered these as predictor variables for our study. From our study it is seen that among the demographic determinants, gender, marital status, and income of the respondents do not influence the choice of political party in our sample. However, occupation and newspaper choice of voters have significant impact on political party choice in our sample. In addition, we have observed that certain categories of age of voters significantly influence decision making of voters along with occupation and newspaper choice categories. 相似文献
9.
目的对蓝色圆珠笔字迹在经过紫外光源老化后的独特特征进行研究,建立确认紫外灯照射的人为老化文件的方法。方法本文以蓝色圆珠笔字迹为研究对象,蓝色圆珠笔中的三芳甲烷类染料在紫外灯的照射下会吸收光子的能量加速其老化脱甲基的反应,通过适当的假设可以推导出其老化程度随时间变化的老化方程,由于目前紫外灯管几乎全部是线型结构,建立合适的坐标系,假设线型灯管能量分布均匀,且紫外线以球面波的形式传播出去,可以计算出纸面上任意一点的能量,通过纸张表面不同位置的三芳甲烷类染料的老化程度的不同来区别自然老化文件与紫外灯人为老化文件的不同。结果经过实验发现对于紫外灯人为老化文件来说甲基紫初始含量比上老化后含量的对数值与紫外灯对于该点的能量的辐出的比值为一个常数K,该K值稳定,浮动范围小,线性关系的置信度大于99%,可以认为两个参数之间存在显著地线性关系,可以证明对于老化方程的推导和能量密度分布函数的推导合理符合实际,对于自然老化文件来说则不存在这种规律。结论可以利用这种特殊的分布规律构建一个衡量这种分布的函数来定量地确认紫外灯照射的人为老化文件。 相似文献
10.
Dana M. Hollinshead Sangwon Kim John D. Fluke Lisa Merkel-Holguin 《Journal of public child welfare》2015,9(5):463-486
Numerous child protective services (CPS) agencies have adopted differential responses as a system reform hypothesized to facilitate family engagement. This research tests a conceptual framework developed to examine dynamics between caregiver, agency, and caseworker factors that are assumed to impact caregiver engagement. Data from a randomized control study and structural equation modeling methods were used to explore the influence of these factors on caregiver satisfaction with their CPS experience. The results indicate that receipt of alternative response, caregivers' ratings of their caseworker's interaction style, and caregivers' positive emotional response influenced satisfaction with their intervention experience, while negative emotional responses did not. 相似文献