Everything else is ready: study the parts, the key terms and the quiz below.
Mean, Median and Mode
Choose the right "typical value", and see the mean pulled by one outlier.
In this lesson7 parts
- 01Decide what one value represents
- 02The mean uses every invoice value
- 03The median locates the middle
- 04The mode counts repeated values
- 05Inspect the extreme invoice before judging it
- 06Choose a summary for the stated report
- 07Reproduce and challenge the summaries
Key terms
The words this lesson introduces, each in one line. The module’s glossary collects them all.
- unit of analysis
- The thing counted once in a summary.
- gross positive invoice value
- The sum of included positive line values for one invoice. It is not net revenue.
- mean
- The sum of observed values divided by their count.
- median
- The middle ordered value, or the average of the two middle values.
- mode
- The most frequent observed value under a stated precision (here, to the penny).
- modal bin
- The histogram interval with the highest count under declared edges.
- right skew
- A distribution with a longer tail toward larger values.
- outlier
- An observation far from most others under a stated comparison. Being unusual does not make it wrong.
- sensitivity check
- Recompute after one stated change to see its effect.
Quiz 5 questions
Your first pick on each question is the one that counts, and a right one earns a coin. Getting one wrong here is how the lesson sticks.
Practice
Problems to solve in your own notebook. Each states the problem, not the steps: working out the steps is the exercise. Level A applies the lesson, B combines it with earlier ones, C stretches it.
The self-checking notebook for this lesson is Invoice centre and spread.
Common mistakes
What you will see when it goes wrong, why it happens, and the fix.
Where it’s used
Where this lesson’s ideas turn up in real work.