Statistics How To

Probability and Statistics > Probability > How to Create an Euler Diagram Euler diagram: Overview An Euler diagram is similar to a Venn diagram. While both use circles to create diagrams, there’s a major difference: Venn diagrams represent an entire set, while Euler diagrams can represent a part of a set. A Venn diagram can … Read more

Descriptive Statistics: Charts and Graphs > The X-MR Chart (X-Moving Range Chart) is a control chart used in process monitoring. While the X-only chart plots processes with individual observations, the X-MR plots a combination of individual measurements and a moving range based on two consecutive measurements. Thus, the X-Moving range chart is a pair of … Read more

Confidence Intervals > Clopper-Pearson The Clopper-Pearson interval, also called the exact interval is an alternative to calculating binomial confidence intervals using normal approximation. It is based on inverting the equal-tailed binomial tests. It is the most commonly cited exact method for finding a confidence interval [1]. The Clopper-Pearson exact method is strictly conservative and therefore … Read more

Statistics Definitions > The mean absolute percentage error (MAPE) — also called the mean absolute percentage deviation (MAPD) — measures accuracy of a forecast system. It measures this accuracy as a percentage, and can be calculated as the average absolute percent error for each time period minus actual values divided by actual values. The mean … Read more

Statistics Definitions > In a data warehouse, data granularity is the level of detail in a model or decision making process. It tells you how detailed your data is: Lower levels of detail equal finer, more detailed, data granularity [1, 2]. Finer, more granulated data will allow you to perform more precise data analysis. For … Read more

Clustering > Fuzzy Clustering What is Fuzzy Clustering? Fuzzy clustering is a clustering method where data points can belong in more than one group (“cluster”). Clustering divides data points into groups based in similarity between items and looks to find patterns or similarity between items in a set; Items in clusters should be as similar … Read more

Bernoulli Distribution > What are Bernoulli Trials? A Bernoulli trial is an experiment with two possible outcomes: Success or Failure. “Success” in one of these trials means that you’re getting the result you’re measuring. For example: If you flip a coin 100 times to see how many heads you get, then the Success is getting … Read more

Regression Analysis > ANCOVA Contents: What is ANCOVA? As an Extension of Multiple Regression An an Extension of ANOVA Within-Group Variance General steps for ANCOVA Assumptions for ANCOVA ANCOVA in SPSS In order to follow this article, you may want to read these articles first: Analysis of Variance (ANOVA) Regression Analysis What is ANCOVA? ANCOVA … Read more

Confidence Intervals > The asymptotic confidence interval is the “textbook” method for constructing confidence intervals. It’s valid for large sample sizes (hence the alternate name, “large-sample” confidence interval) but there are no set guidelines for how large is “large enough” [1]. If you know the distribution for your statistic, you can construct an exact confidence … Read more

Design of Experiments > Research Methods Quantitative Research vs. Qualitative. Quantitative research is statistical: it has numbers attached to it, like averages, percentages or quotas. Qualitative research uses non-statistical methods. For example, you might perform a study and find that 50% of a district’s students dislike their teachers. The quantity (50%) makes it quantitative research. … Read more