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Glossary Archives

Predictive Validity

Predictive Validity: The predictive validity of survey instruments and psychometric tests is a measure of agreement between results obtained by the evaluated instrument and results obtained from more direct and objective measurements. The predictive validity is often quantified by the correlation coefficient between the two sets of measurements obtained for...

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Predicting Filter

Predicting Filter: Predicting filters are filters that estimate the next value in a time series from the known previous values. In contrast to smoothing filters , in predicting filters the output at the moment depends only on the values at preceding moments: . Predicting filters are used in time series...

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Poisson Process (Graphical)

Statistical Glossary Poisson Process: A Poisson process is a random function U(t) which describes the number of random events in an interval [0,t] of time or space. The random events have the properties that (i) the probability of an event during a very small interval from t to t +...

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Polynomial

Statistical Glossary Polynomial: A polynomial of order is a function described by the following expression: where are coefficients of the polynomial. A polynomial of order is the simplest type of polynomial. Its chart, against , is a line. Polynomials are used in regression analysis, multiple regression, time series analysis. In...

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Population

Population: A population is a large set of objects of a similar nature - e.g. human beings, households, readings from a measurement device - which is of interest as a whole. A related concept is a sample , a subset of objects is drawn from a population. An important broad...

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Power Mean

Statistical Glossary Power Mean: A power mean of order of a set of values is defined by the following expression: The family of power mean statistics is often called the generalized mean - because, for different values of the parameter , it is equivalent to various types of descriptive statistics:...

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Nonrecursive Filter

Statistical Glossary Nonrecursive Filter: In nonrecursive filters , the output at the moment is a function of only input values corresponding to the time moments : A complementary concept is recursive filter . Browse Other Glossary Entries

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Odds Ratio (Graphical)

Odds Ratio: The odds ratio compares two probabilities (or proportions) P1 and P2 in the following way: If P1 and P2 are equal, the odds ratio is equal to 1. Browse Other Glossary Entries

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Poisson Distribution (Graphical)

Poisson Distribution: Poisson distribution is a discrete distribution, completely characterized by one parameter : (where k! = 1 x 2 x ... x k). Both the mean and the variance of Poisson distribution are equal to . Poisson distribution describes the number of random events on an interval in space...

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Nonlinear Filter

Statistical Glossary Nonlinear Filter: A nonlinear filter is the filter whose output is a nonlinear function of the input. By definition, any filter that is not a linear filter is a nonlinear filter. One practical reason to use nonlinear filters instead of linear filters is that linear filters may be...

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Noise

Noise: The noise is the component of the observed data (e.g. of a time series ) that is random and carries no useful information. The presence of noise is often the major nuisance factor that makes statistical inference from the data more difficult. The complementary concept is signal . The...

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Multiple Regression (Graphical)

Multiple Regression: Multiple (linear) regression is a regression technique aimed at finding a linear relationship between the dependent variable and multiple independent variables. (See regression analysis.) The multiple regression model is as follows: where Yi are values of the dependent variable, X1i, X2i, ... , Xmi are values of m...

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Multiplicative Error

Statistical Glossary Multiplicative Error: A multiplicative error is proportional to the true value of the quantity being measured. An example of a multiplicative error is when electronic scales provide readings 1% higher than the true weight - i.e. 1.01 kg for 1.0 kg standard weight, 2.02 kg for a 2.0...

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Missing Data Imputation

Statistical Glossary Missing Data Imputation: "Imputing missing data" is a process by which the missing values in a data set are estimated from the remaining data, for the purpose of allowing statistical procedures to be performed on a complete data set. (Most statistical procedures fail if some values in a...

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Monte Carlo Simulation

Monte Carlo Simulation: Monte Carlo simulation is simulation of a random phenomena using pseudo-random numbers . This type of simulation is widely used in practical statistics, e.g. in resampling , in queuing theory . The goal of Monte Carlo simulation is not necessarily simulation of stochastic phenomenon. Monte Carlo simulation...

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Measurement Error

Statistical Glossary Measurement Error: The measurement error is the deviation of the outcome of a measurement from the true value. For example, if electronic scales are loaded with a 1 kilogram standard weight and the reading is 1002 grams, the measurement error is +2 gram (1002 - 1000). Measurement error...

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Median Filter

Statistical Glossary Median Filter: The median filter is a robust filter . Median filters are widely used as smoothers for image processing , as well as in signal processing and time series processing. A major advantage of the median filter over linear filters is that the median filter can eliminate...

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Mean Values (Comparison)

Statistical Glossary Mean Values (Comparison): The numerical example below illustrates basic properties of various descriptive statistics with "mean" in their name, like the arithmetic mean , the trimmed mean , the geometric mean , the harmonic mean , and several power mean . Because the last three statistics are defined...

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