Review 1

Card Set Information

Review 1
2014-01-11 16:38:58

Ch 2
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  1. Categorical Data
    Use labels or names to identify categories of like items
  2. Quantitative data
    Are numerical values that indicate how much or how many
  3. Data visualization
    Term used to describe the use of graphical displays to summarize and present information about a data set
  4. Frequency Distribution
    A tabular summary of data showing the number (frequency) of observations in each of several nonoverlapping categories or classes
  5. Relative & percent frequency
    def. & equation
    • The fraction or proportion of observations belonging to a class.
    • rel freq.=frequency of the class / n
    • n=total observations
    • % freq=relative frequency * 100
  6. Relative & percent frequency distribution
    Gives a tabular (table) summary of data showing the relative frequency for each class
  7. Bar Charts
    graphical display for depicting categorical data summarized in a frequency, relative frequency, or percent frequency distribution. The later stated information is usually on the vertical axis and the classes on the horizontal axis
  8. Pie Charts
    Graphical display for presenting relative frequency and percent frequency distribution for categorical data. Divides a circle into sectors to represent relative freq or % freq distribution
  9. 3 steps necessary to define the classes for a frequency distribution with quantitative data:
    • 1. Determine the number of nonoverlapping classes.
    • 2. Determine the width of each class.
    • 3. Determine the class limits
  10. Number of classes
    General guideline recommends using between 5 and 20 classes. Dependent of the number of data items
  11. Width of classes
    guide & equation
    • general guideline is that the width be the same for each class.
    • Approx. class width= Largest data value - smallest data value / number of classes
  12. Class limits
    An upper and lower class limit must be chosen so that each data item belongs to one and only class.
  13. Dot plot
    A graphical summary of data with a horizontal axis showing the range for the data. Each data value is represented by a dot placed above the axis
  14. Histogram
    Graphical display of quantitative data with the frequency, relative frequency, or % freq. dist. on the vertical axis. The variable of interest on the horizontal axis. Unlike bar chart because it contains no separation between the classes
  15. Cumulative Distributions
    Tabular summary of quantitative data using the number of classes, class width, and class limits developed for the frequency distribution showing the data items with values less than or equal to the upper class limit of each class
  16. Cumulative Relative Frequency Distribution
    • Shows the proportion of data items
    • cum. rel. freq= cum freq / total items n
  17. Cumulative percent frequency distribution
    Shows the percentage of data items with values less than or equal to the upper limit of each class
  18. Stem and leaf display
    A graphical display used to show simultaneously the rank order and shape of data.
  19. 2 Primary advantage of stem and leaf display
    • 1. easier to construct by hand
    • 2. within a class interval more information provided than the histogram because the actual data is shown
  20. Crosstabulation
    tabular summary of data for two variables
  21. Simpson's paradox
    • The reversal of conclusions based on aggregate and unaggregated data.
    • conclusions drawn from two or more separate crosstabulations can be reversed when the data are aggregated into a single crosstabulation.