Confused about a term in elementary probability and statistics? Check out our explanations for statistical terms. Statistics definitions in simple English! Many of the statistics definitions you’ll find here include videos, graphs and charts to make the explanations easier to understand.

## Finding What You Need

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## Statistics Definitions in Alphabetical Order

Jump to A B C D E F G H I J K L M N O P Q R S T U V W Y-Z

## A

- 10% Condition
- Absolute Risk
- Active Variable
- Ad Hoc Analysis
- Addition Rule in Probability
- Additive Tree
- Adjusted R
- Akaike’s Information Criterion
- Allocation Concealment
- Alpha Level
- Alternate Hypothesis
- ANCOVA
- ANOVA
- Area Principle
- Arithmetic Mean
- Assumption of Independence
- Assumption of Normality
- Attributable Risk
- Average Deviation

## B

- Bartlett’s Test
- Base Rates
- Bell Curve
- Benford’s Law
- Benjamini-Hochberg Correction
- Bessel Function
- Beta Level
- Bias
- Bin in Statistics
- Binary Variable
- Binomial Coefficient
- Binomial Distribution Formula
- Bivariate Analysis
- Blinding
- Bootstrap Sample
- Boruvka’s Algorithm
- Bowley Skewness
- Box Cox Transformations
- Box and Whiskers Chart
- Brier Skill Score
- Business Statistics

## C

- C-Statistic
- Cardinal Numbers
- Categorical Variable
- Causation
- Cauchy-Schwarz Inequality
- Censoring
- Central Tendency
- Chauvenet’s Criterion
- Chebyshev’s Inequality
- Chi-Square Statistic
- Classical Probability
- Classical Test Theory
- Cluster Sampling
- Clustered Standard Errors
- Clustering
- Cochran’s Q
- Coefficient of Determination
- Cohen’s Kappa Statistic
- Cohort Study
- Collinear
- Concordance Correlation Coefficient
- Concordant and Discordant Pairs
- Conditional Distribution
- Conditional Probability
- Confidence Level
- Confounding Variable
- Conservative
- Consistent Estimator
- Construct Validity
- Content Validity
- Contingency Table
- Continuity Correction Factor
- Contour Plot
- Control Variable
- Correlation
- Correlation Coefficient Formula
- Correlogram
- Covariance in Statistics
- Cramer-Rao Lower Bound
- Criterion variable
- Cronbach’s Alpha
- Curvilinear

## D

- Data Analysis
- Data Mining
- Data Sets
- Decile
- Density Curve
- Dependent variable
- Design Effect
- Deterministic
- Dichotomous Variable
- Dimensionality
- Direction of Association
- Dispersion
- Dot Plot
- Dummy Variables
- Durbin Watson Test

## E

- Effect Size
- Empirical Research
- Empirical Rule
- Endogenous variable
- Estimator
- ETA squared
- Expected Value Formula
- Expected Monetary Value
- Experimental Design
- Explanatory Variable
- Exploratory Data Analysis
- External Validity
- Extraneous Variable
- Extrapolation

## F

- Factor Analysis
- Factorial!
- F Table
- F Statistic
- False Discovery Rate
- False Positive and Negative
- Fisher’s Exact Test of Independence
- Fisher Information
- Fisher Z
- Five Number Summary
- Fixed Effects
- Friedman’s Test
- Frequency Distribution Table
- Frequency Polygon
- Frequentist Statistics

## G

- Gamma Function
- Geometric Distribution
- Geometric Mean
- Goldfeld Quandt Test
- Gold Standard Test
- Goodness of Fit Test
- Greatest Possible Error
- Greedy Matching Algorithm
- Grouping Variable
- Guttman’s Lambda-2

## H

- Harmonic Mean
- Heterogeneous
- Heteroscedasticity
- Hierarchical Linear Modeling
- Homogeneity
- Hotelling’s T-Squared.
- Hypergeometric Distribution

## I

- IID
- Imaginary Numbers
- Implicit Factors
- Independent Variable
- Inferential Statistics
- Internal Consistency
- Internal Validity
- Interquartile Range
- Interval Estimate
- Interval Scale
- Intervening Variable
- Intraclass Correlation
- Inverse Normal
- Item Response Theory

## J

## K

- Kaplan Meier Analysis
- Kelly’s Measure of Skewness
- Kendall’s Tau
- Kruskal Wallis Test
- Kuder-Richardson
- Kurtosis

## L

- L-Estimator
- Large Enough Sample Condition
- Latent Class Analysis
- Latent Semantic Analysis
- Law of Large Numbers
- Least Squares Regression Line
- Leptokurtic
- Levene Test
- Likelihood Ratio
- Likert Scale
- Line Graph
- Location Parameter
- Logarithms
- Log-Rank test
- Lowess Smoothing

## M

- Manipulated Variable
- Mann Whitney U Test
- Marginal Mean
- Market Basket Analysis
- Matched Samples
- McNemar Test
- Mean
- Mean Error
- Mean Squared Error
- Median
- Median Absolute Deviation
- Method of Moments
- Middle Fifty
- Midrange
- Minimal Detectable Difference
- Minimum Spanning Tree
- Mode
- Monotonic Relationship
- Monty Hall Problem
- Monte Carlo Simulation
- Morisita Index
- Moving Average
- Moment
- Moment Generating Function
- Multicollinearity
- Multidimensional Scaling
- Multinomial Coefficient
- Multiple Imputation

## N

- Negative Binomial Experiment
- Nested Model
- Nominal Variable
- Nominal Ordinal Interval Ratio
- Non-Parametric Data and Tests
- Non Centrality Parameter
- Normal Distribution Probability
- Normal Probability Plot
- Null Hypothesis

## O

## P

- P-Value
- Pairwise average
- Parameter
- Parametric Modeling
- Parametric Tests
- Pareto Principle
- Park Test
- Partial Correlation
- Pascal’s Triangle
- Pearson Correlation
- Pearson Mode Skewness
- Pearson’s Coefficient of Skewness
- Percent Error
- Percentiles
- Permuted Block Randomization
- Phi Coefficient
- Point Biserial Correlation
- Point Estimate
- Poisson Process
- Polya Urn
- Polychoric Correlation
- Population
- Population Mean
- Population Density
- Population Proportion
- Post-hoc
- Power Law
- Power Mean
- Predictive Analytics
- Prim’s Algorithm
- Prime Numbers
- Principal Component Analysis
- Probabilistic Models
- Probability Density Function
- Probability Distribution
- Probability Distribution Table
- Propensity Score Matching
- Proportion of Variance
- Pygmalion Effect
- Purposive Sampling

## Q

## R

- Random Seed
- Range
- Random variable
- Rank Biserial
- Rank Histogram
- Ranked Variable
- Rao Blackwell Theorem
- Rate Parameter
- Rate Ratio
- Ratio Scale
- Real Numbers
- Receiver Operating Characteristic Curve
- Regression Equation
- Reject the Null Hypothesis
- Relative Error
- Relative Precision
- RFM (Customer Value)
- Relative Risk
- Relative Standard Deviation
- Relative Variance
- Reliability
- Rescaling Data
- Residual values
- Residual Sum of Squares
- Resistant Statistics
- Responding Variable
- Richter Scale
- Rician Distribution
- Robust Statistics

## S

- Sample Mean
- Sampling Frame
- Scale Invariance
- Scale Parameter
- Seasonal Kendall Test
- Segmented Bar Chart
- Semantic Differential Scale
- Sensitivity/Specificity
- Serial Correlation
- Sequence Effects
- Shape Parameter
- Shapiro-Wilk Test
- Shifting Data
- Simple linear regression
- Simple Random Sample
- Simpson’s Diversity Index
- Simpson’s Paradox
- Slope Formula
- Snowball Sampling
- Spearman-Brown Formula
- Spearman Rank Correlation
- St. Petersburg Paradox
- Standard Deviation
- Standard Error of Measurement
- Standard Error of a Sample
- Standardized Residuals
- Standardized Variables
- Stanine Score
- Stationarity
- Statistic
- Statistical Analysis
- Statistical Conclusion Validity
- Statistical Power
- Statistical Process Control
- Statistical Relationship
- Statistical Significance
- Statistical Treatment
- STEN Score
- Stratum
- Stratification
- Student’s T-Test
- Sufficient Statistic
- Summary Statistics
- Summation Notation
- Survival Analysis

## T

- T Score
- T Statistic
- Test-Retest Reliability
- Test Statistic
- Tetrachoric Correlation
- Tikhonov Regularization
- Thurstone Scale
- Tukey Ladder of Powers
- Treatment-As-Usual
- Trimean
- Trimmed Mean / Truncated Mean
- Turning Point Test
- Tweedie Distribution
- Two Way Table
- Type I error
- Type I and Type II Errors
- Type III and Type IV Errors

## U

## V

## W

- Weighting Factor
- White Test
- Wilcoxon Signed Rank Sum Test
- Within Mean Square
- Weighted Mean
- W Statistic

## Y/Z

## Style Notes

I try to keep things simple with definitions, using as few words as possible. That’s because these articles are aimed at beginners, or lay people who want an overview. Some people say the articles are *too* simple. If you’re looking for more in depth, head over to Wolfram or Wikipedia. Those places are going to have a lot more formulas, but be prepared to do a bit of translation.

## Why I Started This Site

I remember when I first started learning statistics. I’d look up a term, and what I got was either one sentence (not helpful) or a two page technical manual. Often the words in the manual were ones I didn’t know and they were usually not explained at all. I’d have to go on the hunt for a term and often it would turn into an hours long venture to find what I wanted. What I wanted was simple: an overview of the term so that I could get a general idea of what it was.

Once you’ve got an overview of a topic, then things start to connect in your brain. Things start falling into place. Only then can you go back and tackle the in-depth stuff.

I started this site in 2009 and back then, there was little out there in the way of simple explanations. Now it seems there’s a lot of choices from large sites with articles not written by statisticians. That’s where this site is different:

- I’m a statistician, and I’ve taught statistics at the college/university level.
- I’ve got a graduate degree in education, which means I know how to get my point across in a variety of ways. If you don’t like reading, then there’s usually a video. I’m working on videos all the time to add to articles.
- I have struggled with math my whole life. So I know what it’s like to “not get it.” Give me a page of equations and I still get sweaty palms and a churning stomach.
- This site is for YOU, not me, and I love feedback. The bulk of the articles on here were developed in part with feedback and comments.

I hope you find these statistics definitions useful. But if you don’t, please leave a comment and I’ll be happy to help clarify or expand the article.

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**Questions on statistics definitions**? Post a comment and I’ll do my best to help!