Statistics How To

Statistics Definitions > Greatest Possible Error What is The Greatest Possible Error? The greatest possible error (GPE) is the largest amount a ballpark figure can miss the mark. It’s one half of the measuring unit you are using. For example: If measuring in centimeters, the GPE is 1/2 cm. …or in liters, the GPE is … Read more

Hypothesis Testing > Neyman-Pearson Lemma What is Neyman-Pearson Lemma? The Neyman-Pearson Lemma is a way to find out if the hypothesis test you are using is the one with the greatest statistical power. The power of a hypothesis test is the probability that test correctly rejects the null hypothesis when the alternate hypothesis is true. … Read more

Statistics Definitions > Kullback–Leibler divergence (also called KL divergence, relative entropy information gain or information divergence) is a way to compare differences between two probability distributions p(x) and q(x). More specifically, the KL divergence of q(x) from p(x) measures how much information is lost when q(x) is used to approximate p(x). It answers the question: … Read more

Hypothesis tests > Composite Hypothesis Test What is a Composite Hypothesis Test? A composite hypothesis test contains more than one parameter and more than one model. In a simple hypothesis test, the probability density functions for both the null hypothesis (H0) and alternate hypothesis (H1) are known. In academic and hypothetical situations, the simple hypothesis … Read more

Effect Size > Pooled Standard Deviation What is a Pooled Standard Deviation? The Pooled Standard Deviation is a weighted average of standard deviations for two or more groups. The individual standard deviations are averaged, with more “weight” given to larger sample sizes. Watch the video for an overview and calculation example: Can’t see the video? … Read more

Design of Experiments > Order Effects What are Order Effects? Order effects are where the order of treatments in an experiment matter. In other words, placing the treatments in a different order alter the results. For example, let’s say you are investigating three treatments for depression: Meditation, Exercise, Medication. The treatment plans could be ordered … Read more

Regression Analysis > Tolerance Intervals What is a Tolerance Interval? Tolerance intervals (also called enclosure intervals) are similar to prediction intervals, but they cover a fixed proportion of the population. They are where we expect a certain population proportion to lie. For a particular confidence interval, it tells you lower and upper values which have … Read more

Design of Experiments > Repeated Measures Design What is a Repeated Measures Design? In a repeated measures design, each group member in an experiment is tested for multiple conditions over time or under different conditions. For example, a group of people with Type II diabetes might be given medications to see if it helps control … Read more

Statistics Definitions > Sequence Effects What are Sequence Effects? Sequence effects happen when sequences of conditions in an experiment interact with each other. In other words, earlier events can have an effect later events, or events that happen at the same time can affect each other. They can become confounding variables in an experiment. For … Read more

Experimental Design > What is Blocking? Blocking is where you control sources of variation (“nuisance variables“) in your experimental results by creating blocks (homogeneous groups). Treatments are then assigned to different units within each block. The term blocking comes from agriculture, where different pesticides or growing techniques were used on different plots (or blocks) of … Read more