Summary Statistics

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  • Created by: Cyn:)
  • Created on: 21-02-14 18:18
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  • Summary Statistics
    • Types of variables
      • Quantitative variable
        • Continuous numerical variable.
      • Ordinal variable - interval scale
        • Categories that have an obvious order. E.g: Disease severity ( mild, severe, convalescent).
      • Discrete variable
        • discontinuous numericalvariable
        • Example: Age as a whole number or number of cells in a culture.
      • Categorical variable
        • Sometimes described as nominal
        • Non - numerical values
        • Dichotomus- 2 categories such as female or male.
        • Polytomous- more than 2 categories. E.g: Blood type or types of birds.
    • SAMPLE: collection of individuals or things on which we measure or more variables.
    • POPULATION: total collection of individuals or things from which we have drawn the sample.
    • Measures of CENTRAL TENDENCY
      • is a central value or a typical value for a probability distribution.[1] It is occasionally called anaverage or just the center of the distribution.
        • Apart from Average/mean. The position on the X-axis can be describe by mode or median as well.
          • MODE: the class with the highest frequency.
          • MEDIAN: middle value when in chronological order.
    • Measures of dispersion
      • scatter of data values
        • If values are all the same there is NO DISPERSION.
        • If the values are widely scattered then GREATER DISPERSION.
    • Parametric and non-parametric.
      • Parametric method- oldest method. May not be appropriate for biological data.
        • This method makes assumptions that may not be true.
      • Non- Parametricmethods: new method. NOT based upon stringent assumptions.
        • More suitable for processing biological data. Generally, simpler to use since they avoid long and repetitive calculations,

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