MYP · Mathematics MYP Year 1
Statistics – Averages and Analysis
19 min readFoundationalCore data-handling strand — tested in almost every summative assessment involving Criterion D (Applying mathematics in real-life contexts)
Averages tell you the 'typical' value in a set of numbers — but every average lies a little. Grouping data hides individual values, choosing the wrong average lets an outlier fool you, and misreading a box plot loses easy marks. Almost every question in this topic is testing whether you spot which of those three traps is set for you.
Overview
This chapter has one job: turn a messy pile of numbers into a single sentence someone can act on. To do that you need to organise data (grouping), summarise it (mean, median, mode), describe how spread out it is (range, IQR, box plots), work backwards from an average to fill in gaps, and finally compare two sets fairly.
- Raw data → organised into class intervals when there's too much of it to read at a glance.
- Central tendency (mean, median, mode) answers 'what's typical?' — but each answers it differently.
- Spread (range, IQR) answers 'how consistent is it?' — a missing half of the story if you only quote an average.
- Missing-value questions just run the mean formula in reverse: know the average and the count, and subtraction does the rest.
The shape of the chapter
Command terms that decide your mark
| Command term | What it demands | AO | Mark-earning move |
|---|---|---|---|
| Identify | Pick out or name one specific value from the data or context. | AO1 | The exact correct interval/value gets the mark — no explanation needed, but vague answers ('the third one') don't count as precise. |
| State | Give a short, precise answer with no justification required. | AO1 | A one-line factual answer earns full marks; extra explanation earns nothing extra and wastes time. |
| Describe | Give a detailed account of how or why something happens, in full sentences. | AO2 | Naming a feature with no mechanism = 0. You must explain WHY (e.g. 'the interval hides repeated values so the exact mode is lost') to get the mark. |
| Calculate | Obtain a numerical answer, showing the working. | AO1/AO2 | Method marks are awarded for correct formula/substitution even if the final arithmetic slips — an answer with zero working risks losing marks if it's wrong. |
| Compare | State similarities AND differences between two data sets, referencing both. | AO3 | Describing only one data set's feature without linking it to the other set loses the comparison mark entirely. |
Key point
The exam always wants WHY, not just WHAT. A grouped frequency table trades individual accuracy for a clearer overall pattern — that single trade-off answers most 'reason' and 'limitation' questions in this chapter.
Overview