# Summary Statistics

HideShow resource information
• Created by: Cyn:)
• Created on: 21-02-14 18:18
• 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,