## Poisson's ratio

other two directions perpendicular to the direction of compression. This phenomenon is called the **Poisson** effect . **Poisson** 's **ratio** ν ( nu ) is a measure of the **Poisson** effect. The **Poisson ratio** is the **ratio** of the fraction (or percent) of expansion divided by the fraction (or percent

**wikipedia.org**| 2011/9/28 1:12:34

## Relative risk

is the risk of an event (or of developing a disease) relative to exposure. Relative risk is a **ratio** of the probability of the event occurring in the exposed group versus a non-exposed group. [ 1 ] Consider an example where the probability of developing lung cancer among smokers was

**wikipedia.org**| 2011/5/19 13:50:06

## Poisson number

**Poisson** number From Wikipedia, the free encyclopedia Jump to: navigation , search **Poisson** number can refer to: In mechanics, the reciprocal of **Poisson** 's **ratio** . 1 / v. In statistics, a number drawn from a **Poisson** distribution This disambiguation page lists articles

**wikipedia.org**| 2010/9/25 2:49:34

## Noncentral hypergeometric distributions

In statistics , the hypergeometric distribution is the discrete probability distribution generated by picking colored balls at random from an urn without replacement. Various generalizations to this distribution exist for cases where the picking of colored balls is biased so that balls

**wikipedia.org**| 2010/9/25 4:42:30

## Pentagram map

Exponential shrinking 3 Motivating discussion 4 Coordinates for the moduli space 4.1 Cross **ratio** 4.2 The corner coordinates 4.3 (ab) coordinates 5 Formula for the pentagram map 5.1 As a birational mapping 5.2 As grid compatibility relations 6 Invariant structures

**wikipedia.org**| 2011/7/9 9:39:58

## Index of dispersion

In probability theory and statistics , the index of dispersion , [ 1 ] dispersion index, coefficient of dispersion, or variance-to-mean **ratio** (VMR) , like the coefficient of variation , is a normalized measure of the dispersion of a probability distribution : it is a measure used to

**wikipedia.org**| 2011/4/25 19:45:05

## Data transformation (statistics)

In statistics , data transformation refers to the application of a deterministic mathematical function to each point in a data set — that is, each data point z i is replaced with the transformed value y i = f ( z i ), where f is a function. Transforms are usually applied so that the

**wikipedia.org**| 2011/9/13 14:00:37

## Rasch model

Rasch models are particularly used in psychometrics , the field concerned with the theory and technique of psychological and educational measurement. In addition, they are increasingly being used in other areas, including the health profession and market research because of their general applicability

**wikipedia.org**| 2011/9/14 4:15:19

## Martingale (probability theory)

In probability theory , a martingale is a model of a fair game where no knowledge of past events can help to predict future winnings. In particular, a martingale is a sequence of random variables (i.e., a stochastic process ) for which, at a particular time in the realized sequence, the

**wikipedia.org**| 2011/9/2 16:28:28