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Statistical Science - Coggle Diagram

- - - - Is to determine, for a given question, the type of data that is needed, the way it should be collected and how it should be analyzed in order to best answer that question.
        It can be aplicated to agriculture, medical research, industrial research, forensic science, market research, environmental science, political science and quality assurance. Basically every topic you can imagine.
- - - - Nominal: Categorical data and numbers that are simply used as
        identifiers or names represent a nominal scale of measurement.
        
        Ordinal: An ordinal scale of measurement represents an ordered
        series of relationships or rank order.
        
        Interval: A scale which represents quantity and has equal units
        but for which zero represents simply an additional point of
        measurement is an interval scale.
        
        Ratio: The ratio scale of measurement is similar to the interval
        scale in that it also represents quantity and has equality of units.
  - - - Random sampling is analogous to putting everyone's name into a hat and drawing out several names. Each element in the population has an equal chance of occuring. While this is the preferred way of sampling, it is often difficult to do. It requires that a complete list of every element in the population be obtained.
        
        Systematic sampling is easier to do than random sampling. In systematic sampling, the list of elements is "counted off".
        
        Convenience sampling is very easy to do, but it's probably the worst technique to use. In convenience sampling, readily available data is used. That is, the first people the surveyor runs into.
        
        Cluster sampling is accomplished by dividing the population into groups -- usually geographically. These groups are called clusters or blocks. The clusters are randomly selected, and each element in the selected clusters are used.
        
        Stratified sampling also divides the population into groups called strata. However, this time it is by some characteristic, not geographically. For instance, the population might be separated into males and females. A sample is taken from each of these strata using either random, systematic, or convenience sampling.