We started Chapter 2 by discussing an interesting (and historical) graph by C. Minard who described the movement of Napoleon's army in the 1812-13 Russian campaign. (We also heard a piece of classical music.)
We continued by looking at the shape of a distribution and learned about stem-and-leaf diagrams, dot plots and histograms. In all cases we used MegaStat to draw these graphs. We discussed a method for determining the best value of K and L, and drew a histogram with correct class lengths and number of classes.
We discovered that many data sets are symmetrical, but they could also be positively- and negatively-skewed. (McMaster salaries we looked at were positively-skewed.)
Next, we reviewed the mean, median and mode as measures of central tendency. The variability measures of range (not too useful), variance and standard deviation were introduced. (Recall the example I gave with two buckets of water.) The sample standard deviation has a slightly different formula for which I gave an intuitive explanation.
We will continue with the Empirical Rule for "normal populations" which we did not finish yet.
I plan to complete Chapter 2 next week.
