epib wk 2 - frequency distributions

Frequency distributions - def, characteristics, examples, and aids

• frequency distributions: show the patterns of values in a dataset

  → characteristics:

  • shape: peaks,

  • location:

  • spread (dispersion):

• Aids:

  • stem plot: simple way to visualize data based on the frequency of each value:

    → Steps:

    1. first sort in ascending order

    2. List stems and leaves

    3. list stem values to the left of the axis multiplier

    4. add a vertical line to the right of each stem

  • Frequency tables: to describe the frequency distributions of a variable

    → Types:

    A. Relative frequency: a given value is the frequency divided by the total sample size (often as a %)

    B. Cumulative frequency:

    - only for the first row will it be the same as og frequency

    - not a percentage - only a count

    C. Cumulative relative frequency: combination of RF and CRF

    - can be left as decimal or percent

    - can use RF to add present and past #

  • Histogram: where each bar represents a class interval (x-axis) with the height representing the frequency (y-axis)

class interval frequency table

• range of values

• don’t want overlapping class intervals

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