Statitistics Revivew Ch.1-3

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Author:
morganhchs
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171970
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Statitistics Revivew Ch.1-3
Updated:
2012-09-19 17:51:25
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statistics review
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chapter review
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  1. What is a frequency table?
    • A grouping of qualitative data into mutually exclusive classes showing the number
    • of observations in each class.
  2. What is a Bar Chart?
    • A graph in which the classes are reported on the horizontal axis and the class frequencies on the vertical axis. The class frequencies are proportional to the
    • heights of the bars.
  3. What is a Pie Chart?
    A chart that shows the proportion or percent that each class represents of the total number of frequencies.
  4. What is a Frequency Disribution?
    A grouping of data into mutually exclusive classes showing the number of observations in each class.
  5. Relative Class Frequency
    -Class frequencies can be converted to relative class frequencies to show the fraction of the total numberof observations in each class. 

    -A relative frequency captures the relationship between a class total and the total number of observations.
  6. In frequency distribution what is a class interval?
    Class interval:  The class interval is obtained by subtracting the lower limit of a class from the lower limit of the next class

    .
  7. How to decide on the number of classes for a frequency distiribution.
      A useful recipe to determine the number of classes (k)is the “2 to the k rule.”  such that 2k > n.

    i.e.  There were 180 vehicles sold, so n = 180. If we try k =7, then 27  = 128, somewhat less than 180. Hence, 7 is not enough classes. If we let k = 8, then 28  = 256, which is greater than 180. So the recommended number of classes is 8.
  8. How to determine the class interval or
    width.
    • The formula is: i ≧ (H-L)/k where "i" is the class interval, H is the highest observed value, L is the lowest observed value, and k isthe number of classes.
    • Round up to some convenient number, such as a multiple of 10 or 100. Use a class width of $400
  9. How to determine Relative Frequency Distribution.
    • To convert a frequency distribution to a relative frequency distribution, each of the class frequencies is divided by the total number of observations.

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