2 Introduction Covers numerical measures used as descriptive statistics Box plots (a.k.a. box-and-whisker plots) are introduced (separate vignette)Not all topics in the text will be covered in this vignette
4 Shape – Center - SpreadWhen we gather data, we want to uncover the “information” in it. One easy way to do that is to think of: “Shape –Center- Spread”Shape – What is the shape of the histogram?Center – What is the mean or median?Spread – What is the range or standard deviation?Chapter 2 was the graphical approachChapter 3 uses numerical measures
13 Shape: The “shape” of the data is called its “distribution”? If mean = median = mode, the shape of the distribution is symmetric.If mode < median < mean, the shape of the distribution trails to the right, is positively skewed.If mean < median < mode, the shape of the distribution trails to the left, is negatively skewed.Distributions of various “shapes” have different properties and names such as the “normal” distribution, which is also known as the “bell curve” (among mathematicians it is called the Gaussian Distribution).