1. Summarizing Data in Tables and Graphs

2.  Graphs/Charts for Qualitative Data  Example: Operations Performed at a Hospital last year Thoracic20 Bones and joints45 Eye, ear, nose, and throat58 General98 Abdominal115 Urologic74 Neurosurgery23 Other65

4.  Bar Graph: displays number or percentage of items in each category using bars  Used for qualitative data  The bars can be vertical or horizontal  The height of a bar represents the quantity we wish to compare  The bars should be of uniform width and uniformly spaced

5.  Graphs/Charts for Quantitative Data  Stem and Leaf – separates data entries into “leading digits” or “stems” and “trailing digits” or “leaves”.  A device that organizes and groups data but allows us to recover the original data if desired  Good for spotting extreme values and patterns

6.  Example: 14 male weights in pounds 139,153,179,201,163,168,157,170,172, 165,145,155,161,151

7.  Frequency distribution – a summary table in which the data are arranged into conveniently established class groupings useful when dealing with very large data sets through the grouping process the original data is lost should have between 5 and 15 classes each class grouping should be of equal width overlapping the classes must be avoided  class midpoint – the point halfway between the boundaries of each class

8. Weight Number of males 130 but less than 1401 140 but less than 1501 150 but less than 1604 160 but less than 1704 170 but less than 1803 180 but less than 1900 190 but less than 2000 200 but less than 2101 Total14

9.  Histogram – a picture of a frequency distribution differs from a bar chart in two ways  Used for quantitative data  The bars always touch

11. SymmetricUniform

12. Skewed RightSkewed Left

13. Bimodal

14.  Symmetrical – both sides are the same when the graph is folded vertically  Uniform – every class has equal frequency (bars are the same height)  Skewed Left or Skewed Right – one tail is stretched longer than the other. The direction of the skewness is on the side of the longer tail.  Bimodal – the two classes with largest frequencies are separated by at least one class (can indicate that we are sampling from two populations)