Session 2, Part B:
Line Plots

In This Part: Counting Raisins | Making a Line Plot | Interpreting a Line Plot | Intervals

When there is variation in data, there are many different answers to a statistical question, as your answer must take this variation into account. Frequently, answers to statistical questions are given in the form of intervals -- ranges of values for data. Here are two common ways to use intervals to answer statistical questions:

 1 Naming the interval in which all the data are located; that is, from the minimum data value (Min) to the maximum data value (Max). For example, in the Brand X raisin-count data, the interval is 25 to 31. 2 Naming an interval with the highest concentration of data; that is, an interval with little variation that contains a lot of data. For example, in the raisin-count data, a large proportion (14/17) of the Brand X raisin counts are between 26 and 29 (inclusively); this interval is 26 to 29.

 Video Segment In this video segment, Professor Kader leads a discussion about two potential answers to the question "How many raisins are there in a box?" Consider Paul's and Phil's answers to Professor Kader's question. When might Paul's answer be more useful? How about Phil's? Which answer provides a better overall way of looking at the data? Why? If you're using a VCR, you can find this segment on the session video approximately 17 minutes and 08 seconds after the Annenberg Media logo.

 Sometimes it's useful to answer a statistical question with a single value that you've chosen to represent all of your data. The most frequently occurring value, the mode, may be a good choice. For example, in the Brand X raisin-count data, the most common raisin count is 28, which occurred five times. As we continue, we will encounter two other such representative values, the mean (the arithmetic average of the data set) and the median (the value in the exact center of an ordered list of data).

Next > Part C: Frequency Tables

 Session 2: Index | Notes | Solutions | Video