Math219: Ch02

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lazvertiigo
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282734
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Math219: Ch02
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2014-09-11 12:50:44
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math219 SCC Statistics
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Math 219 Statistics and Probability at SCC Informed Decisions Using Data, Michael Sullivan
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  1. frequency distribution
    A frequency distribution lists each category of data and the number of occurrences for each category of data. The frequencies are the counts of the occurrences for each category.
  2. frequencies
    the counts of the occurrences for each category.
  3. relative frequencytion
    the proportion (or percent) of observations within a category. Formula to compute relative frequency: 

  4. relative frequency distribution
    lists each category of data together with the relative frequency. Note, the total for the relative frequencies should be 1 or 100%.
  5. bar graph
    lists the categories on the horizontal axis, draws rectangles above each category where the height are equal to the category�s frequency or relative frequencyV
  6. Pareto chart
    a bar graph whose bars are drawn in decreasing order of frequency or relative frequency. (Pareto chart is used on nominal categorical variable.)
  7. Where is a Pareto chart used?
    on nominal categorical variable
  8. Why is a side-by-side bar graph used?
    Side-by-side bar graphs is used to compare data from two different categories. Data sets should be compared by using relative frequencies, because different sample or population sizes make comparisons using frequencies somewhat misleading.b
  9. pie chart
    A pie chart is a circle divided into sectors. Each sector represents a category of data. The area of each sector is proportional to the frequency of the category.
  10. How are pie charts useful?
    Pie charts are useful to show the relative proportion of each category, compared to the whole.
  11. Is a pie chart useful for categorical data?
    Not that useful.
  12. histogram
    A histogram is constructed by drawing rectangles for each class of data. The height of each rectangle is the frequency or relative frequency of the class. The width of each rectangle is the same and the rectangles touch each other.
  13. Why aren't we able to directly put continuous data in frequency tables?  How do we resolve this issue?
    We can't place continuous data directly because they do not have any obvious categories, but we are able to create categories using classes, or intervals of numbers.
  14. lower class limit
    the smallest value in the class
  15. upper class limit
    the largest value in the classs
  16. class width
    the difference between consecutive lower class limits
  17. What is another way of representing data that is similar to a histogram?
    Stem-and-Leaf plot
  18. How do you draw a Stem-and-Leaf plot?
    To draw a stem-and-leaf plot, each data value must be broken up into two components: leaf and stem

    The stem consists of all the digits except for the right most one and the leaf consists of the right most digit. For the number 173, for example, the stem would be �17� and the leaf would be �3�.
  19. Describe the steps of constructing a Stem-and-Leaf Plot.
    Step 1. The leaf of the data will be the rightmost most digit. The stem of the data will be all, but the right most digit.

    Step 2. Write the stems in a vertical column in increasing order. Draw a vertical ling to the right of the stems.

    Step 3. Write each leaf corresponding to the stems to the right of the vertical line. Leaf must be in increasing order.
  20. Describe the things to be aware when constructing a stem-and-leaf plot.
    1. Should fit on a page


    2. The leaves should not be too long (no skyscrapers)


    3. The leaves should not be too sparse (no pancakes)


    4. What determines the length of a stem-and-leaf display is the unique leaf digit unit (LDU) that must be selected for the plot.kB
  21. What determines the length of a stem-and-leaf display?
    the unique leaf digit unit (LDU) that must be selected for the plot
  22. What is an LDU?
    • Leaf Digit Unit:  the ordinal number pertaining to the leaf digit.  
    • (i.e. For 3.2 leaf = 0.2, then LDU = 0.1 or tenth; for 32 and leaf = 2, then LDU = 1 as in the one's place)
  23. Identify the shape of distribution:
    Uniform (Symmetric)
  24. Identify the shape of distribution:
    Bell-Shaped (symmetric)
  25. Identify the shape of distribution:
    Skewed Right
  26. Identify the shape of distribution:
    Skewed Left
  27. Uniform distribution
    when each of the values tends to occur with the same frequency
  28. bell-shaped distribution
    A variable has a bell-shaped distribution when most of the values fall in the middle, the frequencies tail off to the left and to the right, and it is symmetric
  29. skewed right distribution
    A variable has a skewed right distribution when the distribution is not symmetric and the tail to the right is longer than the tail to the left
  30. skewed left distribution
    A variable has a skewed left distribution when the distribution is not symmetric and the tail to the left is longer than the tail to the right
  31. time-series data
    If the value of a variable is measured at different points in time, the data is known as time-series data.t
  32. time series plot
    A time series plot is obtained by plotting the time in which a variable is measured on the horizontal axis and the corresponding values of the variable on the vertical axis. Line segments are then drawn connecting the points
  33. Why is a time-series plot very useful?
    Time-series plots are very useful identifying trends in the data over time.

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