Weak identification is a well-known issue in the context of linear structural models. However, for probit models with endogenous explanatory variables, this problem has been little explored. In this ...paper, we study by simulating the behavior of the usual
z
-test and the LR test in the presence of weak identification. We find that the usual asymptotic
z
-test exhibits large level distortions (over-rejections under the null hypothesis). The magnitude of the level distortions depends heavily on the parameter value tested. In contrast, asymptotic LR tests do not over-reject and appear to be robust to weak identification.
This study analyses the extent to which cheating occurs in a real selection setting. A two-stage, unproctored and proctored, test administration was considered. Test score inconsistencies were ...concluded by applying a verification test (Guo and Drasgow Z-test). An initial simulation study showed that the Z-test has adequate Type I error and power rates in the specific selection settings explored. A second study applied the Z-test statistic verification procedure to a sample of 954 employment candidates. Additional external evidence based on item time response to the verification items was gathered. The results revealed a good performance of the Z-test statistic and a relatively low, but non-negligible, number of suspected cheaters that showed higher distorted ability estimates. The study with real data provided additional information on the presence of suspected cheating in unproctored applications and the viability of using item response times as an additional evidence of cheating. In the verification test, suspected cheaters spent 5.78 seconds per item more than expected considering the item difficulty and their assumed ability in the unproctored stage. We found that the percentage of suspected cheaters in the empirical study could be estimated at 13.84%. In summary, the study provides evidence of the usefulness of the Z-test in the detection of cheating in a specific setting, in which a computerized adaptive test for assessing English grammar knowledge was used for personnel selection.
At level 3 the driver still remains “in-the-loop” due to the inability of the automated system to manage a particular driving situation/environment and anthropometric data are still essential in ...design. In that aim anthropometric measurements of 193 Serbian and 50 Libyan female drivers have been collected using standard anthropometric instruments and compared using statistical methods - descriptive statistics with Kolmogorov test for normality, linear regression and correlation analysis and comparison of measured anthropometrics using z test. Results obtained in this study are useful to passenger car designers aimed to compete on autonomy level 3 and show that there exist significant differences between Serbian and Libyan female drivers. Future research on other rarely available anthropometric data for other nationalities is recommended, due to globalization trends and constant migrations.
The Ala Wai Canal is one of the main waterways and watersheds on the island of Oʻahu, but it does not meet EPA water quality standards. Despite being deemed unsafe, during paddling season a number of ...adult and teenage paddling crews practice in the Ala Wai for a variety of reasons. In recent years, more discussion and focus has been turned to improving the water quality of the Ala Wai Canal. By doing a water quality study on two tributaries that feed into the Ala Wai watershed, the research group hoped to determine if there was a statistically significant difference between the mean water quality of the two streams. By measuring 952 samples in Pūkele Stream and 889 samples in Makiki Stream taken every fortnight over a 14-year period, the representative suspended solids entering from the eastern and western sides of Ala Wai Canal are compared statistically. Thus, a good general picture of the average difference in water quality between the tributaries is obtained. Through this sample study, it was found that there is a statistically significant difference between the average water quality of the two streams. This finding implies that there is a big enough difference between the suspended solids in the two streams to prioritize the Pūkele Stream over Makiki Stream for remedial actions.
Purpose
Condition monitoring of squirrel cage induction motors (SCIMs) is indispensible for achieving fault-free working environment. As broken rotor bars (BRBs) are one of the more frequent faults ...in a SCIM especially where direct-on-line starting is indispensible, as in underground mines, a priori knowledge of fault severity in terms of the number of BRBs assists in effective fault monitoring. In this regard, this paper aims to propose a unique empirical relation to facilitate the determination of number of BRB.
Design/methodology/approach
Fast Fourier transform is used to obtain fault sideband amplitudes under varying number of BRBs and load torque for 5.5 kW, 7.5 kW, 10 kW, three-phase, 415 V, 50 Hz SCIMs in MATLAB/Simulink. The nature of variation is decided by an appropriate curve fitting technique for comprehending a unique empirical relation. The proposed empirical relation is validated by bootstrapping and z-test. Furthermore, hardware validation is done using 1 kW laboratory prototype with Labview interface.
Findings
The analytical study reveals the dependence of lower and upper sideband amplitudes on the number of BRBs, load torque and machine rating. Therefore, fault severity in terms of number of BRBs is accurately calculated using the proposed empirical relation if load torque, machine rating and amplitudes of lower and upper sidebands are known.
Originality/value
The unique empirical relation proposed in the present work provides accurate knowledge of fault severity in terms of the number of BRBs. This facilitates maintenance scheduling which shall reduce effective downtime and improve production.
Introduction
This paper describes the leafing, flowering and fruiting phenology of canopy trees in the dry deciduous forest of Bhadra wildlife sanctuary from June 2004 to May 2006.
Method
All the ...woody canopy individuals (> 20 cm girth at breast height) were identified and tagged with a unique number along a transect of approximately 2 Km comprising 157 individuals of 22 species. Observations were made at monthly intervals from June 2004 to May 2006 for leafing, flowering and fruiting phenophases.
Result
Leaf fall starts in September, with a peak in December and January. Leaf initiation begins in February, with a peak in April before the monsoon. Leaf expansion starts in February from pre-monsoon with a peak in May and July during the monsoon. Leaf senescence begins in September to November and peaks in January to March. Flower bud initiates in January with a peak in April and May, and pollination begins in April with a peak in May and July before the monsoon to onset of monsoon. Fruit bud initiates in May with a peak in September and October. Unripened fruit was observed in May with a peak in September and November. Fruit fall begins in November with a peak in March.
Conclusion
Our results show that leafing and flowering activities occur in the summer or pre-monsoon. Fruiting patterns occur during the monsoon to post - monsoon season. Seasonality among various phenophases indicates that leaf senescence flower initiation and fruit fall have strong seasonality.
This study aimed to verify the scope and limitations of
the stimuli of indicators of Color (C), Human movement (M), and Response number
(R) of the Zulliger test through a qualitative analysis of the ...stimuli present
in the Zulliger and the Rorschach, comparisons in expressions of C, M, and R,
and R relations with evaluative inconsistencies on Zulliger. Taking the
Rorschach as a reference, the qualitative analysis indicated a variation from
little equivalence up to an overrepresentativeness of Zulliger stimuli. The
comparisons, made with a sample of 51 subjects tested with the Zulliger and
Rorschach tests and divided into concordant and discordant groups according to
the evaluation of instruments, revealed a significant decrease of C and M for
the Zulliger. We also identified a tendency toward a decrease of R on Zulliger
for the discordant group. The results reveal distinctions between the
instruments, limitations of the Zulliger, and instigate investigations for the
R-Optimized Administration.
Validity Evidence of the Z-Test-SC for Use With Children Villemor-Amaral, Anna Elisa de; Pavan, Pâmela Malio Pardini; Tavella, Raquel Rossi ...
Paidéia cadernos de Psicologia e Educação,
08/2016, Letnik:
26, Številka:
64
Journal Article
Recenzirano
Odprti dostop
Abstract In Brazil, there is a lack of tools to assess the children's affective and cognitive dynamics and investments are needed in research that seeks evidence of validity of some assessment tools ...for that public. The Zulliger test in the Comprehensive System (Zulliger-SC) evaluates the adequacy of reality perception, affects, self-perception, interpersonal relationship and cognitive processing and can be used with children, although there are few studies with this purpose in Brazil. Thus, the aim was to contribute in this field, comparing the performances in different stages of development. The participants were 103 children aged 6 and 12 years old, students from public schools in the state of São Paulo, who answered the test individually in the schools. The Zulliger-SC distinguished the children consistently with what is theoretically expected for their age, bringing some evidence of the Zulliger's validity with children.
Resumen En Brasil, hay relativa falta de herramientas para evaluar la dinámica afectiva y cognitiva de niños, siendo necesario invertir en investigaciones que buscan evidencias de validez de algunas técnicas para esa población. El Zulliger - Sistema Integrado (Zulliger-SI) es un instrumento que evalúa el modo de percibir la realidad, los afectos, la autopercepción, la relación interpersonal y funcionamiento cognitivo y puede ser utilizado con niños, pero hay pocos estudios con ese propósito en Brasil. Por lo tanto, el objetivo fue contribuir en este campo, comparándose las respuestas de niños con distintas edades. Participaran 103 niños de 6 e 12 años, estudiantes de escuelas públicas en el estado de São Paulo, que respondieron al test individualmente en la propia escuela. El Zulliger-SC ha diferenciado los niños consistentemente a lo esperado teóricamente para las edades, contribuyendo para validez de su uso con niños.
Resumo No Brasil, há uma escassez de instrumentos para avaliar a dinâmica afetiva e cognitiva de crianças, sendo necessário investir em pesquisas que busquem evidências de validade de técnicas de avaliação para esse público. O Teste de Zulliger no Sistema Compreensivo (Zulliger-SC) é um instrumento que avalia o modo de apreensão da realidade, afetos, auto-percepção, relacionamento interpessoal e funcionamento cognitivo, sendo indicado para uso com crianças, embora sejam escassos os estudos que demonstrem sua validade. Buscou-se contribuir para preencher essa lacuna, comparando os desempenhos de crianças em diferentes etapas do desenvolvimento. Participaram da pesquisa 103 crianças de 6 e 12 anos, estudantes de escolas públicas do interior do estado de São Paulo, que responderam ao instrumento individualmente, na própria escola. O Zulliger-SC diferenciou os participantes de modo coerente ao esperado teoricamente para suas idades, contribuindo com evidências de validade de uso do Zulliger-SC com crianças.
This paper presents the creation of a table for obstacle course scoring results, for female cadets. The table is created based on the results obtained by female cadets during four years of studying ...at the Military Academy in Belgrade. After creating and applying the scoring table, its influence on female cadets scoring results is investigated. The investigation has shown that the implementation of the scoring table has improved the results of female cadets in the obstacle course test for more than 45 seconds but less than 56 seconds in average. / В данной статье представлен процесс разработки оценочной таблицы по осуществлению результатов курсантками при тестировании прохождения препятственной полосы. Таблица разработана на основании результатов, осуществленных курсантками, в течение их четырехлетнего обучения в Военной академии в Белграде. По разработке и внедрении данной таблицы проведено исследование, с целью установления влияния оценочной таблицы на достижения результатов курсантками в процессе тестирования. Анализ исследования показал, что внедрение оценочной таблицы повлияло на улучшение результатов тестирования по прохождению препятственной полосы, в среднем ускорив темп прохождения на 45 секунд, но не превысив 56 секунд. / U radu je prikazan postupak izrade tablice za bodovanje ostvarenih rezultata kadetkinja prilikom savlađivanja poligona pešadijskih prepreka. Tablica je izrađena na osnovu rezultata koje su kadetkinje ostvarile tokom četvorogodišnjeg školovanja u Vojnoj akademiji u Beogradu. Nakon formiranja i implementacije tablice sprovedeno je istraživanje koje je odgovorilo na pitanje da li uvođenje tablice za bodovanje u proces testiranja kadetkinja utiče na ostvarene rezultate. Pokazano je da je uvođenje tablice za bodovanje kadetkinja popravilo ostvarene rezultate na poligonu pešadijskih prepreka u proseku za 45 sekundi, ali ne za više od 56 sekundi.
Oral health researchers have shown great interest in the relationship between the initial status of diseases and subsequent changes following treatment. Two main approaches have been adopted to ...provide evidence of a positive association between baseline values and their changes following treatment. One approach is to use correlation or regression to test the relationship between baseline measurements and subsequent change (correlation/regression approach). The second approach is to categorize the lesions into subgroups, according to threshold values, and subsequently compare the treatment effects across the two (or more) subgroups (categorization approach). However, the correlation/regression approach suffers a methodological weakness known as mathematical coupling. Consequently, the statistical procedure of testing the null hypothesis becomes inappropriate. Categorization seems to avoid the problem of mathematical coupling, although it still suffers regression to the mean. We show, first, how the appropriate null hypothesis may be established to analyze the relationship between baseline values and change in the correlation approach and, second, we use computer simulations to investigate the impact of regression to the mean on the significance testing of the differences in the average treatment effects (or average baseline values) in the categorization approach. Data available from previous literature are reanalyzed by testing the appropriate null hypotheses and the results are compared to those from testing the usual (incorrect) null hypothesis. The results indicate that both the correlation and categorization approaches can give rise to misleading conclusions and that more appropriate methods, such as Oldham's method and our new approach of deriving the correct null hypothesis, should be adopted.
PDF
