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Glossary Archives

Interquartile Range

Interquartile Range: The difference between the 3d and 1st quartiles is called the interquartile range and it is used as a measure of variability (dispersion). Browse Other Glossary Entries

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Kurtosis

Kurtosis: Kurtosis measures the "heaviness of the tails" of a distribution (in compared to a normal distribution). Kurtosis is positive if the tails are "heavier" then for a normal distribution, and negative if the tails are "lighter" than for a normal distribution. The normal distribution has kurtosis of zero. Kurtosis...

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Life Tables

Life Tables: In survival analysis, life tables summarize lifetime data or, generally speaking, time-to-event data. Rows in a life table usually correspond to time intervals, columns to the following categories: (i) not "failed", (ii) "failed", (iii) censored (withdrawn), and the sum of the three called "the number at risk". Each...

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Likert Scales

Likert Scales: Likert scales are categorical ordinal scale s used in social sciences to measure attitude. Measurements at Likert scales usually take on an odd number of values with a middle point, e.g. "strongly agree", "agree", "undecided", "disagree", "strongly disagree". The middle value is usually labeled "neutral" or "undecided". Forced-choice...

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Log-log Plot

Log-log Plot: A log-log plot represents observed units described by two variables, say x and y , as a scatter graph . In a log-log plot, the two axes display the logarithm of values of the variables, not the values themselves. If the relationship between x and y is described...

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Logit

Logit: Logit is a nonlinear function of probability. If p is the probability of an event, then the corresponding logit is given by the formula:   logit(p) = log  p (1 - p) Logit is widely used to construct statistical models, for example in logistic regression . See also: Logit...

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Logit and Odds Ratio

Logit and Odds Ratio: The following relation between the odds ratio and logit is often used for constructing statistical models:   log  OR(p1, p2) = logit  (p1) - logit  (p2) where p1, p2 are probabilities, OR  (p1, p2) is the odds ratio for p1 and p2 . See also: Logit Models Browse Other Glossary...

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Mean

Mean: For a population or a sample, the mean is the arithmetic average of all values. The mean is a measure of central tendency or location. See also: Expected Value. Browse Other Glossary Entries

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Mean Squared Error

Statistical Glossary Mean Squared Error: The mean squared error is a measure of performance of a point estimator. It measures the average squared difference between the estimator and the parameter. For an unbiased estimator, the mean squared error is equal to the variance of the estimator. Browse Other Glossary Entries

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Median

Median: In a population or a sample, the median is the value that has just as many values above it as below it. If there are an even number of values, the median is the average of the two middle values. The median is a measure of central tendency. The...

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Mode

Mode: The mode is a value that occurs with the greatest frequency in a population or a sample. It could be considered as the single value most typical of all the values. Browse Other Glossary Entries

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Moments

Moments: For a random variable x, its Nth moment is the expected value of the Nth power of x, where N is a positive integer. The Nth moment of the deviation of x from its mean is called "the Nth central moment". The 1st moment is the mean, the 2nd...

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Odds Ratio

Odds Ratio: The odds ratio compares two probabilities (or proportions) P1 and P2 in the following way:   q =  P1/(1-P1) P2/(1-P2) . If P1 and P2 are equal, the odds ratio is equal to 1.   If the symbols do not display properly, try the graphic version of this...

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Order Statistics

Statistical Glossary Order Statistics: The order statistics of a random sample X1, X2, . . ., Xn are the sample values placed in ascending order. They are denoted by X(1), X(2), . . ., X(n) . Here, X(1) X(2) X(n) . For example, for the sample {1 3 7 7...

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Path coefficients

Path coefficients: In path analysis and structural equation modeling a path coefficient is the partial correlation coefficient between the dependent variable and an independent variable, adjusted for other independent variables. Browse Other Glossary Entries

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Percentile

Percentile: In a population or a sample, the Pth percentile is a value such that at least P percent of the values take on this value or less and at least (100-P) percent of the values take on this value or more. See also: quartile, median. Browse Other Glossary Entries

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Pie Icon Plots

Statistical Glossary Pie Icon Plots: Pie icon plots are a sub-class of icon plots . Each unit or observation is represented by a circle with colored "pies slices" corresponding to variables - the angular size of a slice of pie is proportional to the value of the corresponding variable. In...

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Polygon Icon Plots

Statistical Glossary Polygon Icon Plots: Polygon icon plots are a subclass of circular icon plots in which the rays tend to form a polygon. Browse Other Glossary Entries

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