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Morisita's Overlap Index
Morisita's overlap index, named after Masaaki Morisita, is a statistical measure of dispersion of individuals in a population. It is used to compare overlap among samples (Morisita 1959). This formula is based on the assumption that increasing the size of the samples will increase the diversity because it will include different habitats (i.e. different faunas). Formula: : C_D= \frac : ''x''''i'' is the number of times species ''i'' is represented in the total ''X'' from one sample. : ''y''''i'' is the number of times species ''i'' is represented in the total ''Y'' from another sample. : ''D''''x'' and ''D''''y'' are the Simpson's index values for the ''x'' and ''y'' samples respectively. : ''S'' is the number of unique species ''C''''D'' = 0 if the two samples do not overlap in terms of species, and ''C''''D'' = 1 if the species occur in the same proportions in both samples. Horn's modification of the index is (Horn 1966): :C_H= \frac \,. Note, not to be confused with Mo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dispersion (statistics)
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 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 range (IQR) * Range * Mea ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sample (statistics)
In statistics, quality assurance, and survey methodology, sampling is the selection of a subset (a statistical sample) of individuals from within a statistical population to estimate characteristics of the whole population. Statisticians attempt to collect samples that are representative of the population in question. Sampling has lower costs and faster data collection than measuring the entire population and can provide insights in cases where it is infeasible to measure an entire population. Each observation measures one or more properties (such as weight, location, colour or mass) of independent objects or individuals. In survey sampling, weights can be applied to the data to adjust for the sample design, particularly in stratified sampling. Results from probability theory and statistical theory are employed to guide the practice. In business and medical research, sampling is widely used for gathering information about a population. Acceptance sampling is used to determine ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Simpson's Index
A diversity index is a quantitative measure that reflects how many different types (such as species) there are in a dataset (a community), and that can simultaneously take into account the phylogenetic relations among the individuals distributed among those types, such as ''richness'', ''divergence'' or ''evenness''. These indices are statistical representations of biodiversity in different aspects ( richness, evenness, and dominance). Effective number of species or Hill numbers When diversity indices are used in ecology, the types of interest are usually species, but they can also be other categories, such as genera, families, functional types, or haplotypes. The entities of interest are usually individual plants or animals, and the measure of abundance can be, for example, number of individuals, biomass or coverage. In demography, the entities of interest can be people, and the types of interest various demographic groups. In information science, the entities can be charact ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Taylor's Law
Taylor's power law is an empirical law in ecology that relates the variance of the number of individuals of a species per unit area of habitat to the corresponding mean by a power law relationship. It is named after the ecologist who first proposed it in 1961, Lionel Roy Taylor (1924–2007). Taylor's original name for this relationship was the law of the mean. The name ''Taylor's law'' was coined by Southwood in 1966. Definition This law was originally defined for ecological systems, specifically to assess the spatial clustering of organisms. For a population count Y with mean \mu and variance \operatorname (Y), Taylor's law is written : \operatorname (Y) = a\mu^b, where ''a'' and ''b'' are both positive constants. Taylor proposed this relationship in 1961, suggesting that the exponent ''b'' be considered a species specific index of aggregation. This power law has subsequently been confirmed for many hundreds of species. Taylor's law has also been applied to assess the time ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Kyushu University
, abbreviated to , is a Japanese national university located in Fukuoka, on the island of Kyushu. It was the 4th Imperial University in Japan, ranked as 4th in 2020 Times Higher Education Japan University Rankings, one of the top 10 Designated National University and selected as a Top Type university of Top Global University Project by the Japanese government. Kyudai is considered one of the most prestigious research-oriented universities in Japan and is a member of the Alliance of Asian Liberal Arts Universities along with the University of Tokyo, Waseda University, Peking University and others. The history of Kyushu University can be traced back to the medical schools of the Fukuoka Domain (福岡藩 Fukuoka han) established in 1867. The school was reorganized to Fukuoka Medical College of Kyoto Imperial University in 1903 and became independent as Kyushu Imperial University in 1911. Albert Einstein visited the university on December 25, 1922. There are 2,089 foreign st ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Population Ecology
Population ecology is a sub-field of ecology that deals with the dynamics of species populations and how these populations interact with the environment, such as birth and death rates, and by immigration and emigration. The discipline is important in conservation biology, especially in the development of population viability analysis which makes it possible to predict the long-term probability of a species persisting in a given patch of habitat. Although population ecology is a subfield of biology, it provides interesting problems for mathematicians and statisticians who work in population dynamics. History In the 1940s ecology was divided into autecology—the study of individual species in relation to the environment—and synecology—the study of groups of species in relation to the environment. The term autecology (from Ancient Greek: αὐτο, ''aúto'', "self"; οίκος, ''oíkos'', "household"; and λόγος, ''lógos'', "knowledge"), refers to roughly the same fie ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
