Power Analysis

Among the questions that a researcher should ask when planning a study is "How large a sample do I need?" If the sample size is too small, even a well conducted study may fail to answer its research question, may fail to detect important effects or associations, or may estimate those effects or associations too imprecisely. Similarly, if the sample size is too large, the study will be more difficult and costly, and may even lead to a loss in accuracy. Hence, optimum sample size is an essential component of any research. When the estimated sample size can not be included in a study, post-hoc power analysis should be carried out. Approaches for estimating sample size and performing power analysis depend primarily on the study design and the main outcome measure of the study. There are distinct approaches for calculating sample size for different study designs and different outcome measures. Additionally, there are also different procedures for calculating sample size for two approaches of drawing statistical inference from the study results, i.e. confidence interval approach and test of significance approach. This article describes some commonly used terms, which need to be specified for a formal sample size calculation. Examples for four procedures (use of formulae, readymade tables, nomograms, and computer software), which are conventionally used for calculating sample size, are also given.

— Harmonics are found to have deleterious effects on power system equipments including transformers, capacitor banks, rotating machines, switchgears and protective relays. Transformers, motors and switchgears may experience increased losses and excessive heating. Shunt filters are effective in minimizing voltage distortions. This paper describes the voltage distortions generated by non-linear loads. The harmonic specifications such as harmonic factor, characteristic harmonic and non-characteristic harmonic are considered while explaining the paper. With the implementation of a passive filter at the bus with non-linear load, the harmonics are greatly reduced. For the specified power system, at all the buses the total harmonic distortion has been evaluated.

Hans Morgenthau's power analysis combines a philosophical, explanatory and practical approach. In his philosophy, power and the will for domination constitutes the nature of politics. In his explanatory approach power, expressed in terms of interest, provides both the aim of foreign policy and the means for its achievements. The practice of power focuses on the ways states(wo)men need to gauge power to avoid miscalculus and its perils. Although filled with insight about the limits of power analysis, like the reduction of power to military affairs or the hubris of the perfect power assessment, Morgenthau's approach is profoundly contradictory. Whereas he needs an explanatory theory of power to support his meta-physical statements, ultimately, the explanatory theory is not independent of it. While his theory should explain the historical record, the somewhat given lessons of history are the defense for his theory (and hence the theory cannot be independently justified). Whereas power needs to be precisely measurable for any statement of its maximisation and balancing, as the explanatory approach requires, his practical approach insists in the sheer impossibility and political danger of believing in such precise measure, since it undermines the realist quest for prudence.

This analysis will inform the early chapters of a book project on power analysis in International Relations. Morgenthau stands as an example for the awareness that power is used in three different sites at the same time, an awareness often lost in later writers. The different attempts to deal with the tensions and contradictions of using the three sites at the same time will inform the evolution of power analysis in the following chapters.

In this paper, I suggest that most cultural diversity classes in social work are taught from a liberal or conservative multicultural perspective that precludes a power analysis and a critical discussion of whiteness. In order to undo this status quo, social educators and practitioners need to incorporate critical multiculturalismas a tool in subverting racism. A critical multicultural practice includes an analysis of whiteness and a commitment on the part of white social workers to take up an antiracist practice. Pedagogical strategies are described that unmask whiteness. Finally, Stephen Madigan's oppositional whiteness, illustrated in a case vignette, is illustrated as an antiracist practice in which a white social worker/therapist situates his own privilege and becomes an ally.

This paper presents an Operational Transconductance Amplifier realized using Floating Gate MOSFETs only. This can be used as Neuron Activation Function with wide linear range and adaptable threshold level and slope. This circuit is suitable for analog signal processing and neural network applications. This circuit generates log sigmoid and tan sigmoid NAF functions simultaneously. In this circuit the parameters of NAF function can be easily changed by changing voltage at the control gate of FGMOSFET. The linear range of the proposed FGMOSFET based OTA circuit is large and is equal to 2 V with a power supply of +0.75 V. Power analysis and noise analysis of the proposed circuit is performed. Mismatch study is performed using Monte Carlo simulation. TSPICE simulation results using 2 mum N-well process are presented. Layout design of the circuit is done using L-Edit in Tanner Tool.

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In consumer tests, the nine-point hedonic scale has been widely employed for data collection. However, several researchers believe that this scale presents limitations, which decrease its discriminative power. It is thus important to identify alternative scales, presenting better performance than the traditional hedonic scale. This study compared the performance of the “hybrid hedonic scale”, the nine-point hedonic scale, the self-adjusting scale and the ranking scale with respect to: (i) the variability of sensory responses, (ii) discriminating power, (iii) adequacy of the data with ANOVA assumptions and, (iv) ease of use. Eighty consumers evaluated five samples of orange juice using the four above-mentioned scales. Both the scale’s and the sample’s presentation order were balanced among the consumers. Data normality was checked by the Shapiro–Wilks test and homoscedasticity by the Brown–Forsythe test. The discriminating power of the scales was analyzed by psample, the REGWF test and Power Analysis. The ranking test results were evaluated by Friedman’s test and the ease of use by the Cochran–Mantel–Haenszel test. The results evidenced the superiority of the hybrid hedonic scale as compared to the structured and self-adjusting scales both with respect to the discriminating power and the ANOVA assumptions. The structured and hybrid hedonic scales were considered to be significantly easier to use than the self-adjusting scale.

Attempts to study the genetic population structure of large mammals are often hampered by the low levels of genetic variation observed in these species. Polar bears have particularly low levels of genetic variation with the result that their genetic population structure has been intractable. We describe the use of eight hypervariable microsatellite loci to study the genetic relationships between four Canadian polar bear populations: the northern Beaufort Sea, southern Beaufort Sea, western Hudson Bay, and Davis Strait - Labrador Sea. These markers detected considerable genetic variation, with average heterozygosity near 60% within each population. Interpopulation differences in allele frequency distribution were significant between all pairs of populations, including two adjacent populations in the Beaufort Sea. Measures of genetic distance reflect the geographic distribution of populations, but also suggest patterns of gene flow which are not obvious from geography and may reflect movement patterns of these animals. Distribution of variation is sufficiently different between the Beaufort Sea populations and the two more eastern ones that the region of origin for a given sample can be predicted based on its expected genotype frequency using an assignment test. These data indicate that gene flow between local populations is restricted despite the long-distance seasonal movements undertaken by polar bears.

We investigated four stream types in four different bioregions, classified by catchment area and altitude, and stressed by different degrees of organic pollution and habitat alteration. We examined a macro-invertebrate based multimetric approach for Austrian rivers as a potential assessment method within the European Water Framework Directive. Benthic macro-invertebrate data (100 samples including reference sites) were used to develop a mul- timetric index for each stream type and targeted stressors. Sites were pre-classified based on physical, chemical, and land use criteria into five ecological quality classes. More than 200 biological metrics were tested for their sensitivity to the targeted stressors, their spatial and temporal variability and their ability to discriminate between different types and degrees of stress. Metrics for index development were selected to reflect different levels of information including ecosystem, community, and individual levels (Karr, 1991; Barbour et al., 1995; Gerritsen, 1995). Combinations of metrics were selected to distinguish best between non or slightly impaired and stressed sites (evaluated by calculating discrimination efficiency values and power analysis). The resulting four indices comprised seven to nine metrics from five to seven metric categories, and distinguished reference/slightly disturbed sites from stressed sites with close to 100% efficiency. The indices can form the basis for stressor-specific assessment of stream condition.

This paper explores the resistance of MOS Current Mode Logic (MCML) against attacks based on the observation of the power consumption. Circuits implemented in MCML, in fact, have unique characteristics both in terms of power consumption and the dependency of the power profile from the input signal pattern. Therefore, MCML is suitable to protect cryptographic hardware from Differential Power Analysis and similar side-channel attacks. In order to demonstrate the effectiveness of different logic styles against power analysis attacks, two full cores implementing the AES algorithm were realized and implemented with CMOS and MCML technology, and a set of different types of attack was performed using power traces derived from SPICE-level simulations. Although all keys were discovered for CMOS, MCML traces did not presents characteristic that can lead to a successful attack.