AN APPLICATION OF HOTELLING’S T2 TEST FOR THE COMPARISON OF THE VISUAL-ACOUSTIC METHOD IN THE IDENTIFICATION OF INGESTIVE CATTLE BEHAVIOR

The bioacoustic method is an important tool for the identification of the ingestive behavior of ruminants, especially in extensive production systems. This is mainly due to its potential to solve the deficiencies presented by the usual method, which is based on the visual observation of the animals. In this article, we present a study whose main objective is to evaluate the accuracy of the bioacoustic method over the visual method to record the macroactivity of grazing cattle ingestive behavior. The comparison of the methods is made in terms of a multivariate statistical approach based on the use of Hotelling’s T2 test. To verify the test performance in comparing the methods, we developed a simulation study using a resampling approach. The results show that the bioacoustic method can be an effective alternative to the visual method, with the advantage of being a noninvasive method that also allows the analysis of the micro events of ingestive behavior.

Methods of comparison of surface texture based on fractal dimension and Hotelling’s T2 test

Comparative analysis of the surface texture of machine parts can be successfully carried out using statistical tests. The paper presents a methodology of method used to compare the surface texture by applying Hotelling’s T2 test as well as a method used to evaluate surface topography by applying fractal dimension. The tests were carried out on samples produced with the use of face milling process for four types of materials. The following types of steel were used: 40HM, C45, NC6 and WCL. For each type of material, four areas were machined with the same machining parameters. Based on these results a decision was made whether the surfaces, despite the same machining conditions, were significantly different from each other. Furthermore, the analysis indicated that the fractal dimension enabled to characterise signal irregularities in quantitative and qualitative way.

Heteroscedasticity in a two-factors design model

This paper studies the two-factors design model when the heteroscedasticity of variance is present in errors. As can be observed, testing of hypothesis based on the main effects for this design model can be performed using Hotelling's T2 test. Simultaneous confidence intervals are also proposed. Finally, the proposed methodology is applied to a real-life example.

Perceptions of the dimensions of work success of management consultants in South Africa

The primary goal of this study was to contruct an instrument with which to identify the critical dimensions of the job of management consultants. A secondary goal was to determine whether there are any statistically significant differences in the perceptions of subgroups of the sample. The literature was studied and 53 competencies were found. Based on these competencies, the "Management Consulting Competency Questionnaire" (MCCQ) was developed,comprising two sets of items. The first set concerns the importance of various competencies, and the second set relates to the frequency with which the competencies are used. The items were judged by 165 management consultants. Factor analyses were carried out and the resulting factors were further subjected to an interbattery factor analysis. Three factors were identified, namely consulting skills, consultant personality and client service skills. The subgroups were compared using Hotelling's T2 test and MANOVA. Statistically significant differences were found in the perceptions of management consultants for consulting level and years experience. Opsomming Die hoofdoelstelling van die studie was om 'n meetinstrument te konstrueer waarmee die kritieke dimensies van die werk van bestuurskonsultante geidentifiseer kan word. 'n Sekondêre doelstelling was om vas te stel of daar statistics beduidende verskille is tussen die persepsies van subgroepe van die steekproef. Die literatuur is deurskou en 53 bevoegdhede is gevind. Op grond van die bevoegdhede is die "Management Consulting Competency Questionnaire" (MCCQ) ontwikkel, bestaande uit twee stelle items. Die eerste stel het betrekking op die belangrikheid van verskeie bevoegdhede, en die tweede stel op die frekwensie waarmee daardie bevoegdhede gebruik word. Die items is deur 165 bestuurskonsultante beoordeel. Faktorontledings is uitgevoer en die resulterende faktore is verder aan 'n interbatteryfaktorontleding onderwerp. Drie faktore is onttrek, naamlik konsultasievaardighede, konsultantpersoonlikheid en kliëntediensvaardighede. Die subgroepe is vergelyk deur Hotelling se T2 toets en MANOVA te gebruik. Statisties beduidende verskille is gevind in die persepsies van bestuurskonsultante ten opsigte van konsultantvlak en jare ervaring.