Statistics How To

Statistics Definitions > Practical Significance Practical significance relates to whether a result from a statistical hypothesis test is useful in real life. It is a way to address some of the limitations with traditional testing and answers the question Do your results have real life applications and meaning? Statistical significance is used in hypothesis testing … Read more

Statistics Definitions > The term “V statistic” could refer any one of several statistics. Which one you’re using depends on what type of analysis you’re performing. For example: Correlation analysis: Cramer’s V Discriminant analysis: Rao’s V MANOVA: Pillai’s V These statistics are usually called “Cramer’s V, Rao’s V and Pillai’s trace respectively, which avoids the … Read more

Statistics Definitions > When you hear the term Test of Association in statistics, it usually means the Chi-Square Test. However, it’s used in an informal sense to mean many things. Loosely speaking, any time you’re trying to find out if two variables are linked in some way, you’re testing for association. Depending on the context, … Read more

Statistics Definitions > Inductive statistics (or inductive reasoning) is a branch of statistics that deals with taking samples from a larger population and using that data to: Draw conclusions, Make decisions, Forecast, Predict future behavior. For example, you might want to know what if a new, mass-marketed food product is successful, based on consumers’ initial … Read more

Regression Analysis > Weak instruments can wreak havoc with your regression analysis. “Instruments” (instrumental variables) are a third variable, Z, used when you have endogenous variables—variables that are influenced by other variables in the model. Instruments are used to account for unexpected behavior between variables. You are using them to find the true correlation between … Read more

Confounding > A medication’s indication can act as a confounder in observational studies, especially when the drug’s effectiveness is being assessed (Ahrens & Pigeot, 2007). Indication refers to how a particular drug is used for treatment of a certain disease. For example, aspirin is an indication for cardiovascular disease. What is Confounding by Indication? Confounding … Read more

Statistics Definitions > What is Explained Variance? Explained variance (also called explained variation) is used to measure the discrepancy between a model and actual data. In other words, it’s the part of the model’s total variance that is explained by factors that are actually present and isn’t due to error variance. Higher percentages of explained … Read more

Statistics Definitions > What is the Delta Method? The delta method is a way to approximate random variables along with their covariances, means, and variances. The method can also calculate standard errors for complicated statistical estimates. Generally speaking, it is very similar to the Central Limit Theorem. Other names for the delta method, which is … Read more

Descriptive Statistics > A variogram is an effective tool for describing the behavior of non-stationary, spatial random processes. It is used primarily in spatial statistics, geostatistics, and statistical design; In geostatistics, it is an “essential step” for analyzing spatial variability (Gómez-Hernández et al., 1999). The Variogram Function The variogram measures dissimilarity in a relatively simple … Read more

Statistics Definitions > An ARMA model, or Autoregressive Moving Average model, is used to describe weakly stationary stochastic time series in terms of two polynomials. The first of these polynomials is for autoregression, the second for the moving average. Often this model is referred to as the ARMA(p,q) model; where: p is the order of … Read more