Statistics How To

Statistics Definitions > A false alarm ratio, generally abbreviated FAR, is the number of false alarms per the total number of warnings or alarms in a given study or situation. The false alarm ratio is often confused with the false alarm rate, which shares the same abbreviation (FAR). The definitions are different, however; a false … Read more

Descriptive Statistics > A Youden Plot is a type of scatter plot used primarily in plotting results from multiple laboratories on the same graph. It is meant to uncover bias in measurement. Youden Plots are used in medical analysis and quality control, and allow you to see quickly and easily: If labs are equivalent, Which … Read more

Statistics Definitions > An equivalence class is the name that we give to the subset of S which includes all elements that are equivalent to each other. “Equivalent” is dependent on a specified relationship, called an equivalence relation. If there’s an equivalence relation between any two elements, they’re called equivalent. A simple equivalence class might … Read more

Statistics Definitions > You may want to read this article first: What is conditional expectation? What is a Martingale? A martingale is model of a fair game. It is a sequence of random variables x0, x1, x2…xn with one important property: the conditional expectation of xn+1 given x0, x1, x2…xn is always just xn. In … Read more

Types of Bias > What is Membership Bias? Membership bias is when a group of people tend have a specific characteristic that can affect a study’s outcome. Assignment to the group is based on this particular characteristic. In order for a characteristic to create membership bias, group membership can’t be random in any way (Gabay, … Read more

Log Rank Test > The Tarone-Ware test is a variant of the log rank test. It is used in survival analysis to compare two different survival distributions. The test can be used to compare a variety of different situations, including: Two treatment groups in a medical study, Drivers in two different car models in a … Read more

Statistics Definitions > A stress strength model compares the strength and stresses on a system; it is used primarily in reliability engineering but also in economics, psychology and medicine. In a stress strength model both stresses and strength are considered as separate random variables. Stress experienced by a component is often represented by the random … Read more

Bayesian Statistics > A Bayesian estimator is an estimator of an unknown parameter θ that minimizes the expected loss for all observations x of X. In other words, it’s a term that estimates your unknown parameter in a way that you lose the least amount of accuracy (as compared with having used the true value … Read more

Bayesian Statistics > Hyperparameters are model parameters that are estimated without using actual, observed data. It’s basically a “good guess” at what a model’s parameters might be, without using your actual data. More formally, a hyperparameter is a parameter from a prior distribution; it captures the prior belief, before data is observed (Riggelsen, 2008). For … Read more

Homogeneity of Variances > What is Box’s M Test? Box’s M test (also called Box’s Test for Equivalence of Covariance Matrices) is a parametric test used to compare variation in multivariate samples. More specifically, it tests if two or more covariance matrices are equal (homogeneous). Null Hypothesis The null hypothesis for this test is that … Read more