Statistics How To

Statistics Definitions > Relative Error Contents: Relative Error as a Measure of Precision Relative Error as a Measure of Accuracy Relative Error as a Measurement of Precision Relative error (RE)—when used as a measure of precision—is the ratio of the absolute error of a measurement to the measurement being taken. In other words, this type … Read more

Statistics Definitions > Standard Error of Measurement (SEM) What is the Standard Error of Measurement? The standard error of measurement (SEm) is a measure of how much measured test scores are spread around a “true” score. The SEm is especially meaningful to a test taker because it applies to a single score and it uses … Read more

Descriptive Statistics > P-chart / P-Control Chart What is a P-Chart? A p-chart (sometimes called a p-control chart) is used in statistical quality control to graph proportions of defective items. The chart is based on the binomial distribution; each item on the chart has only two possibilities: pass or fail. An “item” could be anything … Read more

Probability > Stochastic Model What is a Stochastic Model? A stochastic model represents a situation where uncertainty is present. In other words, it’s a model for a process that has some kind of randomness. The word stochastic comes from the Greek word stokhazesthai meaning to aim or guess. In the real word, uncertainty is a … Read more

Statistics Definitions > Statistical Relationship What is a Statistical Relationship? Relationships in probability and statistics can generally be one of three things: deterministic, random, or statistical. A statistical relationship is a mixture of deterministic and random relationships. A deterministic relationship involves an exact relationship between two variables. For example, let’s say you earn $10 per … Read more

Statistics Definitions > Brier Score What is a Brier Score? A brier score is a way to verify the accuracy of a probability forecast. A probability forecast refers to a specific event, such as there is a 25% probability of it raining in the next 24 hours. The score can only be used for binary … Read more

Sampling > Bootstrap Sample What is a Bootstrap Sample? A bootstrap sample is a smaller sample that is “bootstrapped” from a larger sample. Bootstrapping is a type of resampling where large numbers of smaller samples of the same size are repeatedly drawn, with replacement, from a single original sample. For example, let’s say your sample … Read more

Design of Experiments > Balanced and Unbalanced Designs What are Balanced and Unbalanced Designs? In ANOVA and Design of Experiments, a balanced design has an equal number of observations for all possible level combinations. This is compared to an unbalanced design, which has an unequal number of observations. Levels (sometimes called groups) are different groups … Read more

Statistics Definitions > Mean Error What is Mean Error? The mean error is an informal term that usually refers to the average of all the errors in a set. An “error” in this context is an uncertainty in a measurement, or the difference between the measured value and true/correct value. The more formal term for … Read more

Regression Analysis > Regularization What is Regularization? Regularization is a way to avoid overfitting by penalizing high-valued regression coefficients. In simple terms, it reduces parameters and shrinks (simplifies) the model. This more streamlined, more parsimonious model will likely perform better at predictions. Regularization adds penalties to more complex models and then sorts potential models from … Read more