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  • Perplex
    IB Math AAHL
    /
    Descriptive Statistics
    /

    Measuring Center

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    Measuring Center

    Measuring Center

    Learn different ways to measure the "center," or typical values, of a set of data: mean, median, and mode.

    Want a deeper conceptual understanding? Try our interactive lesson!

    Exercises

    No exercises available for this concept.

    Key Skills

    Mean
    SL 4.3

    The mean of a numerical dataset is the average of all the values:

    xˉ=number of valuessum of values​🚫


    The mean is also sometimes denoted μ.

    Median
    SL 4.3

    The median of a dataset is the middle value when the values are sorted. If a dataset has an even number of values, the median is the average of the middle two.


    Mathematically, the median is the

    2n+1​th🚫

    value. Notice that if n is even then 2n+1​ is halfway between two consecutive integers, indicating we need to average their values.

    Mode
    SL 4.3

    The mode of a dataset is the most common value in a dataset.


    If all the values have the same frequency ([1,2,3]), there is no mode. If multiple - but not all - values share the highest frequency, then we have multiple modes ([1,2,2,3,3]).