Students will learn from this interactive graphical procedure how individual points can affect the regression line and which outliers exhibit maximal effect. 6 One concept that students often struggle with is the central limit theorem. A picture of the applet is given in Figure 3 . Central Limit Theorem Applet. Each time the dice are rolled, an updated histogram of the sum of the dice is constructed.
Students can study the way the shape of the histogram changes as more observations are generated.
This applet also demonstrates that the central limit theorem applies only when the sample size is relatively large. But for more dice, the histogram will tend to take on the satisfying bell shape, allowing students to see the central limit theorem in action. 10 Students can be left with many misconceptions after a standard introductory discussion. Students also tend to misinterpret the confidence interval by considering it to be a fixed quantity, not recognizing its dependence on the particular sample observed. This can result from the fact that confidence intervals are generally discussed in reference to a particular dataset rather than a series of datasets.