1.  Multiple choice questions…grab handout!

3. Data Analysis: Displaying Quantitative Data

4.  In any graph, we look for the overall pattern and for striking departures from that pattern. We describe the overall pattern with shape, center, and spread.  We describe departures from the pattern with outliers, individuals that fall outside of the overall pattern.  As a mnemonic device we sometime call describing a distribution “checking our SOCS,” or “remembering our SOCS.”

5.  A distribution is roughly symmetric if the right and left sides of the graph are approximately mirror images of each other.  A distribution is skewed to the right if the right side of the graph (containing half of the observations with larger values) is much longer than the left side.  Similarly to skewed to the right, a distribution is skewed to the left if the left side of the graph (containing half the observations with smaller values) is much longer than the right side.

6.  Other common types of shape are: unimodal or having a single peak, bimodal or having two peaks, multimodal or having many peaks, moundlike or resembling a single mound or hill, and normal which we will define and cover in detail later.

7.  The common measures of center we use are mean, median, and mode. ◦ Mean is the average of a data set ◦ Median is the middle value of the data set ◦ Mode is the value that appears most often.  Range is the numerical representation of the distance between the largest and smallest value in a data set.  Standard Deviation and Variance are also measures of spread, these will be covered in detail in the next section

8.  Shape?  Center?  Spread?  Potential Outliers?

9.  How many pairs of shoes does a typical teenager have? Here are the results from a random sample: 50, 26, 26, 31, 57, 19, 24, 22, 23, 38, 13, 50, 13, 34, 23, 30, 49, 13, 15, 51

10.  Quantitative Variables!  A bar graph with no gaps in between.  The frequencies are the heights of the bars.  The x-axis is divided into “classes” or intervals.

13. Class60-6970-7980-8990-99100-109110-119120-129130-139 Freq  75, 65, 121, 100, 101, 89, 114, 63, 123, 127, 100, 96, 116, 109, 92, 131, 134, 105, 108, 117, 90, 89, 101, 101, 89, 98, 104, 130, 128, 97, 113, 129, 106, 87, 107, 68

14.  Shape determines the measure of center, and center determines the measure of spread.  Outliers will always be calculated the same way, independent of shape.  When graphing, don’t confuse histograms (quantitative data) and bar graphs (categorical data).

15.  Pg 42 (37, 39, 41-47, 50-52, 58-62, 64, 66-68)