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Georg Rasch
Georg William Rasch () (21 September 1901 – 19 October 1980) was a Danish mathematician, statistician, and psychometrician, most famous for the development of a class of measurement models known as Rasch models. He studied with R.A. Fisher and also briefly with Ragnar Frisch, and was elected a member of the International Statistical Institute in 1948. In 1919, Rasch began studying mathematics at the University of Copenhagen. He completed a master's degree in 1925 and received a doctorate in science with thesis director Niels Erik Nørlund in 1930. Rasch married in 1928. Unable to find work as a mathematician in the 1930s, he turned to work as a statistical consultant. In this capacity, he worked on a range of problems, including problems of biological growth. Contributions to psychometrics Georg Rasch is best known for his contributions to psychometrics. His work in this field began when he used the Poisson distribution to model the number of errors made by students when re ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Danes
Danes (, ), or Danish people, are an ethnic group and nationality native to Denmark and a modern nation identified with the country of Denmark. This connection may be ancestral, legal, historical, or cultural. History Early history Denmark has been inhabited by various Germanic peoples since ancient times, including the Angles, Cimbri, Jutes, Herules, Teutones and others. A 2025 study in ''Nature'' found genetic evidence of an influx of central European population after about 500 ce into the region later ruled by the Danes. Viking Age The first mention of Danes within Denmark is on the Jelling Rune Stone, which mentions the conversion of the Danes to Christianity by Harald Bluetooth in the 10th century. Between and the early 980s, Bluetooth established a kingdom in the lands of the Danes, stretching from Jutland to Scania. Around the same time, he received a visit from a German missionary who, by surviving an ordeal by fire according to legend, convinced Harold t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Niels Erik Nørlund
Niels Erik Nørlund (26 October 1885, in Slagelse – 4 July 1981, in Copenhagen) was a Denmark, Danish mathematician. His book ''Vorlesungen über Differenzenrechnung'' (1924, reprinted 1954) was the first book on complex analysis, complex function solutions of difference equations. His doctoral students include Georg Rasch. The Norlund Alps and Norlund Land in Greenland were named after him. He was also the brother of Margrethe Bohr, Margrethe Nørlund Bohr and brother-in-law of Nobel Prize winning physicist Niels Bohr. Selected works * * with René Lagrange as editor: * * See also * Nörlund–Rice integral * Inge Lehmann References Further readingMathematics and Mathematicians: Mathematics in Sweden Before 1950 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
1980 Deaths
Events January * January 4 – U.S. President Jimmy Carter proclaims a grain embargo against the USSR with the support of the European Commission. * January 6 – Global Positioning System time epoch begins at 00:00 UTC. * January 9 – In Saudi Arabia, 63 Islamist insurgents are beheaded for their part in the siege of the Great Mosque in Mecca in November 1979. * January 14 – Congress (I) party leader, Indira Gandhi returns to power as the Prime Minister of India. * January 20 – At least 200 people are killed when the Corralejas Bullring collapses at Sincelejo, Colombia. * January 21 – The London Gold Fixing hits its highest price ever of $843 per troy ounce ($2,249.50 in 2020 when adjusted for inflation). * January 22 – Andrei Sakharov, Soviet scientist and human rights activist, is arrested in Moscow. * January 26 – Israel and Egypt establish diplomatic relations. * January 27 – Canadian Caper: Six United States diplomats, posing as Canadians, mana ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Psychometricians
Psychometrics is a field of study within psychology concerned with the theory and technique of measurement. Psychometrics generally covers specialized fields within psychology and education devoted to testing, measurement, assessment, and related activities. Psychometrics is concerned with the objective measurement of latent constructs that cannot be directly observed. Examples of latent constructs include intelligence, introversion, mental disorders, and educational achievement. The levels of individuals on nonobservable latent variables are inferred through mathematical modeling based on what is observed from individuals' responses to items on tests and scales. Practitioners are described as psychometricians, although not all who engage in psychometric research go by this title. Psychometricians usually possess specific qualifications, such as degrees or certifications, and most are psychologists with advanced graduate training in psychometrics and measurement theory. In a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Danish Statisticians
Danish may refer to: * Something of, from, or related to the country of Denmark People * A Danish person, also called a "Dane", can be a national or citizen of Denmark (see Demographics of Denmark) * Culture of Denmark * Danish people or Danes, people with a Danish ancestral or ethnic identity * A member of the Danes, a Germanic tribe * Danish (name), a male given name and surname Language * Danish language, a North Germanic language used mostly in Denmark and Northern Germany * Danish tongue or Old Norse, the parent language of all North Germanic languages Food * Danish cuisine * Danish pastry, often simply called a "Danish" See also * Dane (other) * * Gdańsk * List of Danes * Languages of Denmark The Kingdom of Denmark has only one official language, Danish, the national language of the Danish people, but there are several minority languages spoken, namely Faroese, German, and Greenlandic. A large majority (about 86%) of Danes also ... {{disambigu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Elected Members Of The International Statistical Institute
{{disambiguation ...
Elected may refer to: * "Elected" (song), by Alice Cooper, 1973 * ''Elected'' (EP), by Ayreon, 2008 *The Elected, an American indie rock band See also *Election An election is a formal group decision-making process whereby a population chooses an individual or multiple individuals to hold Public administration, public office. Elections have been the usual mechanism by which modern representative d ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Educational Psychology
Educational psychology is the branch of psychology concerned with the scientific study of human learning. The study of learning processes, from both cognitive psychology, cognitive and behavioral psychology, behavioral perspectives, allows researchers to understand individual differences in intelligence, cognitive development, Affect (psychology), affect, motivation, self-regulation, and self-concept, as well as their role in learning. The field of educational psychology relies heavily on quantitative methods, including testing and measurement, to enhance educational activities related to instructional design, classroom management, and assessment, which serve to facilitate learning processes in various educational settings across the lifespan.Snowman, Jack (1997). Educational Psychology: What Do We Teach, What Should We Teach?. "Educational Psychology", 9, 151-169 Educational psychology can in part be understood through its relationship with other disciplines. It is informed primar ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sufficient Statistics
In logic and mathematics, necessity and sufficiency are terms used to describe a conditional or implicational relationship between two statements. For example, in the conditional statement: "If then ", is necessary for , because the truth of is guaranteed by the truth of . (Equivalently, it is impossible to have without , or the falsity of ensures the falsity of .) Similarly, is sufficient for , because being true always implies that is true, but not being true does not always imply that is not true. In general, a necessary condition is one (possibly one of several conditions) that must be present in order for another condition to occur, while a sufficient condition is one that produces the said condition. The assertion that a statement is a "necessary ''and'' sufficient" condition of another means that the former statement is true if and only if the latter is true. That is, the two statements must be either simultaneously true, or simultaneously false. In ordinary ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Item Response Theory
In psychometrics, item response theory (IRT, also known as latent trait theory, strong true score theory, or modern mental test theory) is a paradigm for the design, analysis, and scoring of Test (student assessment), tests, questionnaires, and similar instruments measurement, measuring abilities, attitudes, or other variables. It is a theory of testing based on the relationship between individuals' performances on a test item and the test takers' levels of performance on an overall measure of the ability that item was designed to measure. Several different statistical models are used to represent both item and test taker characteristics. Unlike simpler alternatives for creating scales and evaluating questionnaire responses, it does not assume that each item is equally difficult. This distinguishes IRT from, for instance, Likert scaling, in which ''"''All items are assumed to be replications of each other or in other words items are considered to be parallel instruments". By contrast ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
United States
The United States of America (USA), also known as the United States (U.S.) or America, is a country primarily located in North America. It is a federal republic of 50 U.S. state, states and a federal capital district, Washington, D.C. The 48 contiguous states border Canada to the north and Mexico to the south, with the semi-exclave of Alaska in the northwest and the archipelago of Hawaii in the Pacific Ocean. The United States asserts sovereignty over five Territories of the United States, major island territories and United States Minor Outlying Islands, various uninhabited islands in Oceania and the Caribbean. It is a megadiverse country, with the world's List of countries and dependencies by area, third-largest land area and List of countries and dependencies by population, third-largest population, exceeding 340 million. Its three Metropolitan statistical areas by population, largest metropolitan areas are New York metropolitan area, New York, Greater Los Angeles, Los Angel ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Poisson Distribution
In probability theory and statistics, the Poisson distribution () is a discrete probability distribution that expresses the probability of a given number of events occurring in a fixed interval of time if these events occur with a known constant mean rate and independently of the time since the last event. It can also be used for the number of events in other types of intervals than time, and in dimension greater than 1 (e.g., number of events in a given area or volume). The Poisson distribution is named after French mathematician Siméon Denis Poisson. It plays an important role for discrete-stable distributions. Under a Poisson distribution with the expectation of ''λ'' events in a given interval, the probability of ''k'' events in the same interval is: :\frac . For instance, consider a call center which receives an average of ''λ ='' 3 calls per minute at all times of day. If the calls are independent, receiving one does not change the probability of when the next on ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Psychometrics
Psychometrics is a field of study within psychology concerned with the theory and technique of measurement. Psychometrics generally covers specialized fields within psychology and education devoted to testing, measurement, assessment, and related activities. Psychometrics is concerned with the objective measurement of latent constructs that cannot be directly observed. Examples of latent constructs include intelligence, introversion, mental disorders, and educational achievement. The levels of individuals on nonobservable latent variables are inferred through mathematical modeling based on what is observed from individuals' responses to items on tests and scales. Practitioners are described as psychometricians, although not all who engage in psychometric research go by this title. Psychometricians usually possess specific qualifications, such as degrees or certifications, and most are psychologists with advanced graduate training in psychometrics and measurement theory. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
