Arithmetic Mean |
Arithmetic mean is a synonym for average, i.e., the sum of all values in a list divided by the number of values present. |

Binomial Distribution |
The binomial distribution is a discrete probability distribution of obtaining exactly *n* successes out of *N* trials. |

Box-and-Whisker Plot |
A box-and-whiskers plot is a histogram-like method of displaying data. |

Central Limit Theorem |
The central limit theorem states that any set of variates with a distribution having a finite mean and variance tends to the normal distribution. This allows statisticians to approximate sets of data with unknown distributions as being normal. |

Chi-Squared Test |
The chi-squared test is a statistical test for evaluating hypotheses involving enumerated data. |

Conditional Probability |
Conditional probability is the probability of an event, assuming that some other event has already occurred. |

Confidence Interval |
A confidence interval is an interval in which a measurement or trial falls that corresponds to a given probability. |

Correlation Coefficient |
The correlation coefficient measure of how closely a best-fit curve matches the given data. |

Covariance |
The covariance of a set of variables is a measure of the strength of their correlation. |

Erf |
The error function, commonly denoted erf, is the function involved in integrating the normal distribution. |

Histogram |
A histogram is a visual grouping of data into bins, plotting the number of members in each bin against the bin number. |

Hypothesis |
(1) In the mathematical and physical sciences, the term hypothesis is often used as a rough synonym for conjecture . (2) In statistics, a hypothesis is a statement that can be tested. (3) In logic, a hypothesis is the first part of a logical implication. |

Independent Events |
Events are said to be independent if the occurrence of one does not influence the probability that the others will occur. |

Law of Large Numbers |
The law of large number is one of several mathematical theorems expressing the idea that as the number of trials of a random process increases, the percentage difference between the expected and actual result values goes to zero. |

Least Squares Fitting |
A mathematical procedure for finding the best-fitting curve to a given set of points by minimizing the sum of the curve's squared offsets from the data. |

Mean |
In statistics, a mean is quantity corresponding to one of possibly several different definitions of the "average" of a set of values, such as the arithmetic, geometric, or harmonic mean. In the absence of additional context, the term "mean" most commnly refers to the arithmetic mean (i.e., the average). |

Median |
(1) In statistics, the median is an order statistic that gives the "middle" value of a sample. (2) In geometry, the median of a triangle is a line segment from one of its vertices to the midpoint of the opposite side. |

Mode |
The mode of a set of observations is the most commonly occurring value. A distribution with a single mode is said to be unimodal. A distribution with more than one mode is said to be bimodal, trimodal, etc., or in general, multimodal. |

Moment |
In statistics, a moment is a measure of the expected deviation from the mean. The most important example of a moment is the variance. |

Normal Distribution |
The normal distribution is a probability distribution associated with many sets of real-world data. Due to the shape of this distribution, it is also famously called the "bell curve." |

Outlier |
In statistics, an outlier is a point in a sample that has a substantially different value from the rest. |

Paired *t*-Test |
The paired t-test is a statistical test that determines whether the means of two sample sets differ significantly. |

Poisson Distribution |
The Poisson distribution is the statistical distribution giving the probability of obtaining exactly *n* successes in *N* trials for Poisson processes such as radioactive decay and lotteries. |

Probability |
Probability is the branch of mathematics that studies the possible outcomes of given events together with the outcomes' relative likelihoods and distributions. |

Problem |
A problem is an exercise whose solution is desired. Mathematical problems may therefore range from simple puzzles to examination and contest problems to propositions whose proofs require insightful analysis and high-level knowledge. |

Sample |
In mathematics, a sample of a population is a subset that is obtained to investigate the parent population's properties. |

Scatter Diagram |
A scatter diagram is a graphic which shows data where one variable has been plotted against a second variable. Scatter diagrams are used when investigating correlation between two variables. |

Standard Deviation |
The standard deviation is a statistic defined as the square root of the variance that measures how spread out a set of data is. |

Statistical Test |
A statistical test is a test used to determine the statistical significance of an observation. |

Statistics |
Statistics is the mathematical study of the likelihood and probability of events occurring, based on known information and inferred by taking a limited number of samples. |

Uniform Distribution |
A uniform distribution is a probability distribution that has constant probability. |

Variance |
In statistics, variance is the measure of the expected deviation from the mean. The square root of the variance is the standard deviation. |

z-Score |
A z-score, also called a "standard score," is the difference from the mean divided by the standard deviation. |