Learn the different characteristics of data

1
Chapter 2
Learn the different characteristics of data
2
Section 2-1

• Important terms CVDOT
• Center Middle, average or mean or representative
  of the data set
• Variation How the data values vary among
  themselves
• Distribution The nature or shape of the
  distribution
  
  
  
  
  
  
  
  (Bell-shaped, uniformed, or
  skewed)
• Outliers Sample values very different or far
  away from the majority
• Time How these data change characteristics over
  time

3
Section 2-2

• Frequency Distribution List data values with
  their frequencies Table 2-2 p39
• Frequency for a class is the number of values
  that fall into this class
• Lower class limits are the smallest values that
  belong to different classes

4
Section 2-2 Continued

• Upper class limits are the largest values that
  belong to different classes
• Class boundaries are numbers used to separate
  classes without gaps. To find class boundaries,
  add 0.5 to the upper class and subtract 0.5 from
  the lower class

5
Section 2-2 Continued

• Class midpoints Add lower and upper classes
  divided by 2
• Class width is the difference between two
  consecutives lower class limits or boundaries
• See Tables and Examples PP3940

6
How to construct a Frequency Distribution?

• Use Common sense
• First, decide on the number of classes you want
  (usually between 5 and 20) then find your class
  width by using
• CW (HV LV) of classes (Round your answer
  up if needed)
• Pp4041

7
Section 2-2 Continued

• After that, everything is simple and common
  sense. Choose your lower limit, add the class
  width to it to get the next lower limit. Do a
  tally to count the number of elements in each
  class.
• Be careful not to overlap classes
• Use same width for each class
• Do not leave any class out (even if Freqzero)
• Now lets try 15-20 p45 while we continue ?

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Relative Frequency and Cumulative Frequency

• Relative Frequency
• Class Frequency Sum of all frequencies
• Table 2-3 p41
• Cumulative Frequency
• Sum of previous classes and actual class
• Table 2-4 p43
• Please read pp42-44 for the importance and the
  interpretation of frequency distribution!
• Suggested HW
• P44 1,3,5,11,17,19

9
Section 2-3

• This section is really about constructing graphs,
  but what is more important is to understand the
  nature of the distribution.
• Here are some of the graphs
• Histogram Bar graph with horizontal scale
  represents the value of the class and vertical
  scale represents frequencies. Ex p46

10
Section 2-3 continued

• Relative Frequency Histogram Vertical scales are
  marked with relative frequencies- Figure 2-2 p46
• Frequency Polygon Line segment with points
  denoted the midpoints
• Figure 2-3 p48
• Ogive Line graph that shows the cumulative
  frequencies, just like cumulative distribution-
  Figure 2-4 p48

11
Section 2-3 continued

• DotPlot Line plot with equal values stacked-
  Figure 2-5 p48
• Stem-and-leaf plots Separate values into the
  leftmost digit(s) as stem and rightmost digit(s)
  as leaf Ex.PP49-50
• Pareto Charts Bar graphs in order according to
  frequencies- Figure 2-6 p51
• Pie Charts Circle graphs- Figure 2-7 p51

12

• Suggested HW
• Pp44-45 1 -18
• Pp 55-59 1-12 17-22 25 26 29-32