Chi Square (Contingency Tables) We have looked at hypothesis tests to analyze the proportion of one population vs. a specified value, and the proportions of two populations, but what do we do if we want to analyze more than two populations? A chi-square test is a hypothesis test in which the sampling distribution of the […]
Why we use a Run Chart A run chart is a chart used to present data in time order. These charts capture process performance over time. The X axis indicates time and the Y axis shows the observed values. A run chart is similar to a scatter plot in that it shows the relationship between X and […]
What is a Box Cox Transformation? Box Cox Transformation Formula The formula of the Box Cox transformation is: Where: Use Minitab to Perform a Box-Cox Transformation Minitab provides the best Box-Cox transformation with an optimal λ that minimizes the model SSE (sum of squared error). Here is an example of how we transform the non-normally […]
What is Multiple Linear Regression? Multiple linear regression is a statistical technique to model the relationship between one dependent variable and two or more independent variables by fitting the data set into a linear equation. The difference between simple linear regression and multiple linear regression: Multiple Linear Regression Equation Where: Both dependent and independent variables […]
What is Simple Linear Regression? Simple linear regression is a statistical technique to fit a straight line through the data points. It models the quantitative relationship between two variables. It is simple because only one predictor variable is involved. It describes how one variable changes according to the change of another variable. Both variables need […]
Pearson’s Correlation Coefficient Pearson’s correlation coefficient is also called Pearson’s r or coefficient of correlation and Pearson’s product moment correlation coefficient (r), where r is a statistic measuring the linear relationship between two variables. What is Correlation? Correlation is a statistical technique that describes whether and how strongly two or more variables are related. Correlation […]
What is the One Sample Wilcoxon Test? The one sample Wilcoxon test is a hypothesis test to compare the median of one population with a specified value. It is an alternative test of one sample t-test when the distribution of the data is non-normal. It is more powerful than one sample sign test but it assumes […]
What is the One Sample Proportion Test? One sample proportion test is a hypothesis test to compare the proportion of one certain outcome (e.g. the number of successes per the number of trials, or the number of defects per the total number of opportunities) occurring in a population following the binomial distribution with a specified […]
Kruskal Wallis One-Way Analysis of Variance The Kruskal Wallis one-way analysis of variance is a statistical hypothesis test to compare the medians among more than two groups. It is an extension of Mann–Whitney test. While the Mann–Whitney test allows us to compare the samples of two populations, the Kruskal–Wallis test allows us to compare the […]
What is Mood’s Median Test? Mood’s median test is a statistical test to compare the medians of two or more populations. The symbol k is the number of groups of our interest and is equal to or greater than two. Mood’s median is an alternative to Kruskal–Wallis. For the data with outliers, Mood’s median test […]
What is the Mann Whitney Test? The Mann Whitney test (also called Mann–Whitney U test or Wilcoxon rank-sum test) is a statistical hypothesis test to compare the medians of two populations that are not normally distributed. In a non-normal distribution, the median is the better representation of the center of the distribution. Where: Mann Whitney […]
What is One Way ANOVA? One way ANOVA is a statistical method to compare means of two or more populations. It is a generalized form of the two sample t-test since a two sample t-test compares two population means and one-way ANOVA compares k population means where k ≥ 2. Assumptions of One Way ANOVA […]
