Statistics · Averages & range
Chapter 1 · 3
The idea
Averages from a frequency table
Mean, median, mode and range from a discrete frequency table — why the mean is the sum of the fx column divided by the total FREQUENCY, not by the number of rows, and how to run it backwards to find a missing frequency.
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Statistics · Averages & range
Averages from a frequency table
Mean, median, mode and range from a discrete frequency table — why the mean is the sum of the fx column divided by the total FREQUENCY, not by the number of rows, and how to run it backwards to find a missing frequency.
Why it works
A compressed list
A frequency table is not a new kind of data. It is a compressed list. Somebody wrote down twenty numbers, noticed how much repetition there was, and squashed them onto four lines:| Goals scored, | Frequency, |
|---|---|
| 0 | 5 |
| 1 | 8 |
| 2 | 4 |
| 3 | 3 |
— twenty numbers, in order, with nothing lost. Every average you already know is still the same average of that list; the table just lets you compute it without writing the list out.
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The rest of the explanation, plus 3 worked examples you step through move by move.
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