Coefficient of variation and Power Pen's parade computation

Under the the assumption that income y is a power function of its rank among n individuals, we approximate the coefficient of variation and gini index as functions of the power degree of the Pen's parade. Reciprocally, for a given coefficient of variation or gini index, we propose the analytic expression of the degree of the power Pen's parade; we can then compute the Pen's parade.Gini index, Income inequality, Ranks, Har- monic Number, Pen's Parade.

The distribution of McKay's approximation for the coefficient of variation

McKay's approximation for the coefficient of variation is type II noncentral beta distributed and asymptotically normal with mean n - 1 and variance smaller than 2(n - 1)

Studies of the coefficient of variation of the magnitude of EEG signals

An analysis of the variation in magnitude of EEG signals in various frequency bands of anesthetized patients and normal sleeping volunteers was carried out. The coefficient of variation (CoV), i.e. the standard deviation/mean, within 10 second epochs was found to be quite constant throughout the whole of the EEG recordings and was typically about 0.46. This was found to be the case for both the patients and the volunteers. Histograms of the magnitudes indicated that the magnitudes are distributed as f(x)=βxe(-αx2) functions. However a CoV of 0.46 is consistent with f(x)=βxe(-αx3) functions. The non-stationary nature of the EEG is such that it is likely that while over short periods the EEG magnitudes are distributed as f(x)=βxe(-αx3) functions, variations of α over time mean that in the long term the EEG magnitudes are distributed as f(x)=βxe(-αx2) functions

Change detection in SAR time-series based on the coefficient of variation

This paper discusses change detection in SAR time-series. Firstly, several statistical properties of the coefficient of variation highlight its pertinence for change detection. Then several criteria are proposed. The coefficient of variation is suggested to detect any kind of change. Then other criteria based on ratios of coefficients of variations are proposed to detect long events such as construction test sites, or point-event such as vehicles. These detection methods are evaluated first on theoretical statistical simulations to determine the scenarios where they can deliver the best results. Then detection performance is assessed on real data for different types of scenes and sensors (Sentinel-1, UAVSAR). In particular, a quantitative evaluation is performed with a comparison of our solutions with state-of-the-art methods

Characterization of rat bone marrow lymphoid cells. I. A study of the distribution parameters of sedimentation velocity, volume and electrophoretic mobility

Various cell populations in rat bone marrow were characterized by means of a two dimensional separation using velocity sedimentation and free flow electrophoresis and by electrical sizing of the separated cells. Up to 4.5 mm/hr five different populations with discrete distributions in volume (coefficient of variation 10% to 13%) and sedimentation velocity (coefficient of variation 6% to 10%) were observed. Three of the small sized populations represented lymphocytes and small normoblasts and two of the larger sized populations represented myeloid cells. Almost all of these cells were in the G0/G1 cycle phase. In the faster sedimenting fractions which contained immature myeloid, erythroid and undefined blast cells and two S phase populations, discrete volume distributions were not evaluated. The cell populations with homogeneous volume (particularly the small lymphocytes) showed high density variations which condiserably impair the separation resolution. The cells sedimenting slower than 3.5 mm/hr were further separated by means of free flow electrophoresis into three peaks differing in electrophoretic mobility (EPM). The peaks of low and high EPM contained two populations and the peak of medium EPM contained three populations all characterized by normal volume distributions of uniform coefficient of variation between 11% and 14%. The small cells in the peaks of high and medium EPM were normolblasts and the other cells were lymphocytes. The biological significance of these results is discussed

Variability of rainfall over small areas

A preliminary investigation was made to determine estimates of the number of raingauges needed in order to measure the variability of rainfall in time and space over small areas (approximately 40 sq miles). The literature on rainfall variability was examined and the types of empirical relationships used to relate rainfall variations to meteorological and catchment-area characteristics were considered. Relations between the coefficient of variation and areal-mean rainfall and area have been used by several investigators. These parameters seemed reasonable ones to use in any future study of rainfall variations. From a knowledge of an appropriate coefficient of variation (determined by the above-mentioned relations) the number rain gauges needed for the precise determination of areal-mean rainfall may be calculated by statistical estimation theory. The number gauges needed to measure the coefficient of variation over a 40 sq miles area, with varying degrees of error, was found to range from 264 (10% error, mean precipitation = 0.1 in) to about 2 (100% error, mean precipitation = 0.1 in)