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Variability (other)
Variability is how spread out or closely clustered a set of data is. Variability may refer to: Biology *Genetic variability, a measure of the tendency of individual genotypes in a population to vary from one another *Heart rate variability, a physiological phenomenon where the time interval between heart beats varies *Human variability, the range of possible values for any measurable characteristic, physical or mental, of human beings Other sciences *Climate variability, changes in the components of Earth's climate system and their interactions * Spatial variability, when a quantity that is measured at different spatial locations exhibits values that differ across the locations *Statistical variability, a measure of dispersion in statistics See also * Variability hypothesis, nineteenth century hypothesis that males have a greater range of ability than females * Variable (other) *Variable renewable energy, a renewable energy source of a fluctuating nature *Variance, a spe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Genetic Variability
Genetic variability is either the presence of, or the generation of, genetic differences. It is defined as "the formation of individuals differing in genotype, or the presence of genotypically different individuals, in contrast to environmentally induced differences which, as a rule, cause only temporary, nonheritable changes of the phenotype." Genetic variability in a population promotes biodiversity, as it ensures that no two living things are exactly alike. While many factors can cause genetic variability, some factors can also decrease genetic variability. Species variability refers to the observable differences within a species, often encompassing morphological, physiological, behavioral, or phenotypic traits. While genetic variability contributes to species variability, external factors like the environment or developmental conditions can also influence the traits expressed. Causes There are many sources of genetic variability in a population: *Homologous recombination is a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Heart Rate Variability
Heart rate variability (HRV) is the physiological phenomenon of variation in the time interval between heartbeats. It is measured by the variation in the beat-to-beat interval. Other terms used include "cycle length variability", "R–R variability" (where R is a point corresponding to the peak of the QRS complex of the ECG wave; and R–R is the interval between successive Rs), and "heart period variability". Measurement of the RR interval is used to derive heart rate variability. Methods used to detect beats include ECG, blood pressure, ballistocardiograms, and the pulse wave signal derived from a photoplethysmograph (PPG). ECG is considered the gold standard for HRV measurement because it provides a direct reflection of cardiac electric activity. Variability Variability (or Variation) in the beat-to-beat interval is a physiological phenomenon. Power spectral analysis of the beat-to-beat variations of heart rate or the heart period (R–R interval) partitions the total va ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Human Variability
Human variability, or human variation, is the range of possible values for any characteristic, human biology, physical or psychology, mental, of human, human beings. Frequently debated areas of variability include cognitive ability, personality, Human physical appearance, physical appearance (body shape, skin color, etc.) and immunology. Variability is partly heritability, heritable and partly Environment (biophysical), acquired (''nature vs. nurture'' debate). As the human species exhibits sexual dimorphism, many traits show significant variation not just between populations but also sex differences in humans, between the sexes. Sources of human variability Human variability is attributed to a combination of environmental and genetic sources including: For the genetic variables listed above, few of the traits characterizing human variability are controlled by simple Mendelian inheritance. Most are polygenic or are determined by a complex combination of genetics and envir ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Climate Variability
Climate variability includes all the variations in the climate that last longer than individual weather events, whereas the term climate change only refers to those variations that persist for a longer period of time, typically decades or more. ''Climate change'' may refer to any time in Earth's history, but the term is now commonly used to describe contemporary climate change, often popularly referred to as global warming. Since the Industrial Revolution, the climate has increasingly been affected by human activities. The climate system receives nearly all of its energy from the sun and radiates energy to outer space. The balance of incoming and outgoing energy and the passage of the energy through the climate system is Earth's energy budget. When the incoming energy is greater than the outgoing energy, Earth's energy budget is positive and the climate system is warming. If more energy goes out, the energy budget is negative and Earth experiences cooling. The energy moving t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Spatial Variability
Spatial variability occurs when a quantity that is measured at different spatial locations exhibits values that differ across the locations. Spatial variability can be assessed using spatial descriptive statistics such as the range. Let us suppose that the Rev' z(x) is perfectly known at any point x within the field under study. Then the uncertainty about z(x) is reduced to zero, whereas its spatial variability still exists. Uncertainty is closely related to the amount of spatial variability, but it is also strongly dependent upon sampling. Geostatistical analyses have been strictly performed to study the spatial variability of pesticide sorption and degradation in the field. Webster and Oliver provided a description of geostatistical techniques. Describing uncertainty using geostatistics is not an activity exempt from uncertainty itself as variogram In spatial statistics the theoretical variogram, denoted 2\gamma(\mathbf_1,\mathbf_2), is a function describing the degree o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Statistical Variability
In statistics, dispersion (also called variability, scatter, or spread) is the extent to which a distribution is stretched or squeezed. Common examples of measures of statistical dispersion are the variance, standard deviation, and interquartile range. For instance, when the variance of data in a set is large, the data is widely scattered. On the other hand, when the variance is small, the data in the set is clustered. Dispersion is contrasted with location or central tendency, and together they are the most used properties of distributions. Measures of statistical dispersion A measure of statistical dispersion is a nonnegative real number that is zero if all the data are the same and increases as the data become more diverse. Most measures of dispersion have the same units as the quantity being measured. In other words, if the measurements are in metres or seconds, so is the measure of dispersion. Examples of dispersion measures include: * Standard deviation * Interquartile r ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Variability Hypothesis
The variability hypothesis, also known as the greater male variability hypothesis, is the hypothesis that human males generally display greater variability in traits than human females do. It has often been discussed in relation to human cognitive ability, where some studies appear to show that males are more likely than females to have either very high or very low Intelligence quotient, IQ test scores. In this context, there is controversy over whether such sex-based differences in the variability of intelligence exist, and if so, whether they are caused by genetic differences, environmental conditioning, or a mixture of both. Sex-differences in variability have been observed in many abilities and traits – including physical, psychological and genetic ones – across a wide range of sexual dimorphism, sexually dimorphic species. On the genetic level, the greater phenotype variability in males is likely to be associated with human males being a heterogametic sex, while females ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Variable (other)
Variable may refer to: Computer science * Variable (computer science), a symbolic name associated with a value and whose associated value may be changed Mathematics * Variable (mathematics), a symbol that represents a quantity in a mathematical expression, as used in many sciences * Propositional variable, taking the value true or false in mathematical logic * Random variable, a variable in statistics whose value depends on random events ** Categorical variable, taking one of a finite number of values in a statistical problem, such as the head or tail result of a tossed coin ** Independent and identically distributed random variables, statistically independent and having the same probability distribution * Fluent (mathematics), a time-varying quantity as coined by Isaac Newton in his early calculus * State variable, used to describe the mathematical "state" of a dynamical system * Slack variable, inserted to transform an inequality constraint in an optimization problem into ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Variable Renewable Energy
Variable renewable energy (VRE) or intermittent renewable energy sources (IRES) are renewable energy sources that are not dispatchable due to their fluctuating nature, such as wind power and solar power, as opposed to controllable renewable energy sources, such as dammed hydroelectricity or bioenergy, or relatively constant sources, such as geothermal power. The use of small amounts of intermittent power has little effect on grid operations. Using larger amounts of intermittent power may require upgrades or even a redesign of the grid infrastructure. Options to absorb large shares of variable energy into the grid include using storage, improved interconnection between different variable sources to smooth out supply, using dispatchable energy sources such as hydroelectricity and having overcapacity, so that sufficient energy is produced even when weather is less favourable. More connections between the energy sector and the building, transport and industrial sectors may also ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Variance
In probability theory and statistics, variance is the expected value of the squared deviation from the mean of a random variable. The standard deviation (SD) is obtained as the square root of the variance. Variance is a measure of dispersion, meaning it is a measure of how far a set of numbers is spread out from their average value. It is the second central moment of a distribution, and the covariance of the random variable with itself, and it is often represented by \sigma^2, s^2, \operatorname(X), V(X), or \mathbb(X). An advantage of variance as a measure of dispersion is that it is more amenable to algebraic manipulation than other measures of dispersion such as the expected absolute deviation; for example, the variance of a sum of uncorrelated random variables is equal to the sum of their variances. A disadvantage of the variance for practical applications is that, unlike the standard deviation, its units differ from the random variable, which is why the standard devi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
