|
Experimental Unit
In statistics, a unit is one member of a set of entities being studied. It is the main source for the mathematical abstraction of a "random variable". Common examples of a unit would be a single person, animal, plant, manufactured item, or country that belongs to a larger collection of such entities being studied. Experimental and sampling units Units are often referred to as being either experimental units, sampling units or units of observation: * An "experimental unit" is typically thought of as one member of a set of objects that are initially equal, with each object then subjected to one of several experimental treatments. Put simply, it is the smallest entity to which a treatment is applied. * A "sampling unit" is typically thought of as an object that has been sampled from a statistical population. This term is commonly used in opinion polling and survey sampling. For example, in an experiment on educational methods, methods may be applied to classrooms of students. This w ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Statistics
Statistics (from German language, German: ''wikt:Statistik#German, Statistik'', "description of a State (polity), state, a country") is the discipline that concerns the collection, organization, analysis, interpretation, and presentation of data. In applying statistics to a scientific, industrial, or social problem, it is conventional to begin with a statistical population or a statistical model to be studied. Populations can be diverse groups of people or objects such as "all people living in a country" or "every atom composing a crystal". Statistics deals with every aspect of data, including the planning of data collection in terms of the design of statistical survey, surveys and experimental design, experiments.Dodge, Y. (2006) ''The Oxford Dictionary of Statistical Terms'', Oxford University Press. When census data cannot be collected, statisticians collect data by developing specific experiment designs and survey sample (statistics), samples. Representative sampling as ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Independent And Identically Distributed Random Variables
In probability theory and statistics, a collection of random variables is independent and identically distributed if each random variable has the same probability distribution as the others and all are mutually independent. This property is usually abbreviated as ''i.i.d.'', ''iid'', or ''IID''. IID was first defined in statistics and finds application in different fields such as data mining and signal processing. Introduction In statistics, we commonly deal with random samples. A random sample can be thought of as a set of objects that are chosen randomly. Or, more formally, it’s “a sequence of independent, identically distributed (IID) random variables”. In other words, the terms ''random sample'' and ''IID'' are basically one and the same. In statistics, we usually say “random sample,” but in probability it’s more common to say “IID.” * Identically Distributed means that there are no overall trends–the distribution doesn’t fluctuate and all items in t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Oscar Kempthorne
Oscar Kempthorne (January 31, 1919 – November 15, 2000) was a British statistician and geneticist known for his research on randomization-analysis and the design of experiments, which had wide influence on research in agriculture, genetics, and other areas of science. Born in St Tudy, Cornwall and educated in England, Kempthorne moved to the United States, where he was for many decades a professor of statistics at Iowa State University. Randomization analysis Kempthorne developed a randomization-based approach to the statistical analysis of randomized experiments, which was expounded in pioneering textbooks and articles. Kempthorne's insistence on randomization followed the early writings of Ronald Fisher, especially on randomized experiments. Kempthorne is the founder of the "Iowa school" of experimental design and analysis of variance. Kempthorne and many of his former doctoral students have often emphasized the use of the randomization distribution under the null hypothe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Unit Of Analysis
The unit of analysis is the entity that frames what is being looked at in a study, or is the entity being studied as a whole. In social science research, at the macro level, the most commonly referenced unit of analysis, considered to be a society is the state (polity) (i.e. country). At meso level, common units of observation include groups, organizations, and institutions, and at micro level, individual people. Unit of analysis vs the level of analysis Unit of analysis is closely related to the term level of analysis, and some scholars have used them interchangingly, while others argue for a need for distinction. Ahmet Nuri Yurdusev wrote that "the level of analysis is more of an issue related to the framework/context of analysis and the level at which one conducts one's analysis, whereas the question of the unit of analysis is a matter of the 'actor' or the 'entity' to be studied". Manasseh Wepundi noted the difference between "the unit of analysis, that is the phenomenon a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Statistical Model
A statistical model is a mathematical model that embodies a set of statistical assumptions concerning the generation of Sample (statistics), sample data (and similar data from a larger Statistical population, population). A statistical model represents, often in considerably idealized form, the data-generating process. A statistical model is usually specified as a mathematical relationship between one or more random variables and other non-random variables. As such, a statistical model is "a formal representation of a theory" (Herman J. Adèr, Herman Adèr quoting Kenneth A. Bollen, Kenneth Bollen). All Statistical hypothesis testing, statistical hypothesis tests and all Estimator, statistical estimators are derived via statistical models. More generally, statistical models are part of the foundation of statistical inference. Introduction Informally, a statistical model can be thought of as a statistical assumption (or set of statistical assumptions) with a certain property: that ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sample Point
In probability theory, an elementary event, also called an atomic event or sample point, is an event which contains only a single outcome in the sample space. Using set theory terminology, an elementary event is a singleton. Elementary events and their corresponding outcomes are often written interchangeably for simplicity, as such an event corresponding to precisely one outcome. The following are examples of elementary events: * All sets \, where k \in \N if objects are being counted and the sample space is S = \ (the natural numbers). * \, \, \, \text \ if a coin is tossed twice. S = \ where H stands for heads and T for tails. * All sets \, where x is a real number. Here X is a random variable with a normal distribution and S = (-\infty, + \infty). This example shows that, because the probability of each elementary event is zero, the probabilities assigned to elementary events do not determine a continuous probability distribution. Probability of an elementary event Elementa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Laboratory Specimen
Need In medicine, a laboratory specimen is a biological specimen of a medical patient's tissue, fluids, or other material used for laboratory analysis to assist in differential diagnosis or staging of a disease process. For example, to detect breast cancer, the breast tissue is biopsied, and the extracted specimen is sent to a lab for analysis and testing. This method of testing often yields extremely high levels of accuracy, with a reported 1-2% of cases having incorrect biopsy results General areas for cellular tissue extraction: * Bone marrow aspiration * Cardiac * Core * Endometrial biopsy * Endoscopic biopsy * Excisional and incisional * Fine-needle aspiration * Lymph node Preparation After extraction, all specimen containers are required to be labeled with at least two of the following identifiers (at the time of collection): patient's name, date of birth, hospital number, test request form number, accession number, or unique random number. Afterwards, all specimen ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Census Tract
A census tract, census area, census district or meshblock is a geographic region defined for the purpose of taking a census. Sometimes these coincide with the limits of cities, towns or other administrative areas and several tracts commonly exist within a county. In unincorporated areas of the United States these are often arbitrary, except for coinciding with political lines. Census tracts represent the smallest territorial entity for which population data are available in many countries. In the United States, census tracts are subdivided into block groups and census blocks. In Canada they are divided into dissemination areas. In the U.S., census tracts are "designed to be relatively homogeneous units with respect to population characteristics, economic status, and living conditions" and "average about 4,000 inhabitants". By country Brazil The Brazilian Institute of Geography and Statistics uses the term census sector (''setor censitário'')''.'' As of the 2010 Census, there ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Units Of Measurement
A unit of measurement is a definite magnitude (mathematics), magnitude of a quantity, defined and adopted by convention or by law, that is used as a standard for measurement of the same kind of quantity. Any other quantity of that kind can be expressed as a multiple of the unit of measurement. For example, a length is a physical quantity. The metre (symbol m) is a unit of length that represents a definite predetermined length. For instance, when referencing "10 metres" (or 10 m), what is actually meant is 10 times the definite predetermined length called "metre". The definition, agreement, and practical use of units of measurement have played a crucial role in human endeavour from early ages up to the present. A multitude of System of measurement, systems of units used to be very common. Now there is a global standard, the International System of Units (SI), the modern form of the metric system. In trade, weights and measures is often a subject of governmental r ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Statistical Assembly
In statistics, for example in statistical quality control, a statistical assembly is a collection of parts or components which makes up a statistical unit In statistics, a unit is one member of a set of entities being studied. It is the main source for the mathematical abstraction of a "random variable". Common examples of a unit would be a single person, animal, plant, manufactured item, or country .... Thus a statistical unit, which would be the prime item of concern, is made of discrete components like organs or machine parts. The reliability of the statistical unit is, in part, determined by the reliability of the components in the statistical assembly, and by their interactions. Much of the observation of a statistical assembly requires special preparation of the unit, which demands that the intervention must not prejudice the observations. A simple version of this kind of research uses the stimulus-response model. In other contexts, statistical assembly refers to the proces ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pseudoreplication
Pseudoreplication (sometimes unit of analysis error) has many definitions. Pseudoreplication was originally defined in 1984 by Stuart H. Hurlbert as the use of inferential statistics to test for treatment effects with data from experiments where either treatments are not replicated (though samples may be) or replicates are not statistically independent. Subsequently, Millar and Anderson identified it as a special case of inadequate specification of random factors where both random and fixed factors are present. It is sometimes narrowly interpreted as an inflation of the number of samples or replicates which are not statistically independent. This definition omits the confounding of unit and treatment effects in a misspecified F-ratio. In practice, incorrect F-ratios for statistical tests of fixed effects often arise from a default F-ratio that is formed over the error rather the mixed term. Lazic defined pseudoreplication as a problem of correlated samples where correlation i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
