Statistics How To

Regression Analysis > Unstandardized coefficients are ‘raw’ coefficients produced by regression analysis when the analysis is performed on original, unstandardized variables. Unlike standardized coefficients, which are normalized unit-less coefficients, an unstandardized coefficient has units and a ‘real life’ scale. An unstandardized coefficient represents the amount of change in a dependent variable Y due to a … Read more

Statistics Definitions > What is Relative Absolute Error? Relative Absolute Error (RAE) is a way to measure the performance of a predictive model. It’s primarily used in machine learning, data mining, and operations management. RAE is not to be confused with relative error, which is a general measure of precision or accuracy for instruments like … Read more

Statistics Definitions > In the real word, uncertainty (sometimes called error or bias) is a part of everyday life, but in statistics we try to quantify just how much uncertainty is in our experiment, survey or test results. The two main types are epistemic (things we don’t known because of a lack of data or … Read more

Statistics Definitions > “Quasi-Statistical” is a somewhat loose term that could refer to: Quasi-experiments Becker’s Quasi-statistics 1. Quasi-Experimental Design A quasi-experimental design is missing one or more key components of a solid experimental design, which are: Pre-post test design. Treatment and control groups. Random assignment of subjects to groups. For more information on this type … Read more

ANOVA > Between group variation is used in ANOVA (analysis of variance) to measure variation between separate groups of interest. Unlike within group variation, where the focus is on the differences between a population and its mean, between group variation is concerned with finding how the means of groups differ from each other. Between Group … Read more

Statistics Definitions > A scale factor is a number which multiplies (“scales”) a quantity. For example,the “C” in y = Cx is the scale factor for x. If the equation were y = 5x, then the factor would be 5. Scale Factor Error These errors involve a proportional multiplier to a true measurement. For example, … Read more

Statistics Definitions > What is the Ceiling Effect? A ceiling effect happens when your questionnaire or test components/problems aren’t hard enough; An artificially low ceiling is created that is easy to achieve. If it exists in your test or survey, it becomes a problem when you’re trying to compare two groups with a hypothesis like … Read more

Statistics Definitions > What is an Error Bar? An error bar is a (usually T-shaped) bar on a graph that shows how much error is built in to the chart. The “error” here isn’t a mistake, but rather a range or spread of data that represents some kind of built in uncertainty. For example, the … Read more

Hypothesis Testing > A directional test is a hypothesis test where a direction is specified (e.g. above or below a certain threshold). For example you might be interested in whether a hypothesized mean is greater than a certain number (you’re testing in the positive direction on the number line), or you might want to know … Read more

Matrices > A confusion matrix, in predictive analytics, is a two-by-two table that tells us the rate of false positives, false negatives, true positives and true negatives for a test or predictor. We can make a confusion matrix if we know both the predicted values and the true values for a sample set. In machine … Read more