MYP Maths: Measures of Central Tendency & Spread

Measures of central tendency (mean, median, mode) tell you where the 'middle' of a data set sits, while measures of spread (range, interquartile range, standard deviation) tell you how scattered the values are around that centre. In MYP Maths, statistics and probability form one of four content areas alongside number, algebra, and geometry & trigonometry.

The mean is the arithmetic average (sum of values ÷ how many there are). The median is the middle value once the data's ordered. The mode is the value that occurs most often. Each answers 'what's typical?' slightly differently — and one bad outlier can distort the mean but barely touch the median.

Spread (or dispersion) describes how bunched together or spread out a data set is. Two classes could have the same mean test score but very different spreads — one tightly clustered around the average, one with huge highs and lows. Range, interquartile range (IQR) and standard deviation all measure this in different ways.

Because the mean (or median) alone can hide the full picture. Two data sets can share an identical mean but tell completely different stories once you look at spread — one consistent, one erratic. MYP's 'Applying mathematics in real-life contexts' criterion specifically rewards students who interpret both together, not just calculate one.

Multiply each value by its frequency and divide the total by the number of data points for the mean. Use cumulative frequency to locate the median's position. The mode is simply the value with the highest frequency. Work through it systematically — rushing the cumulative frequency step is the most common mistake I see.

Order the data, split it into lower and upper halves, then find the median of each half — those are Q1 and Q3. The IQR is Q3 minus Q1. It tells you the spread of the middle 50% of your data, ignoring extreme outliers at either end.

Find the mean, then find how far each value deviates from it, square those deviations, average them (this gives variance), then take the square root. Standard deviation tells you the typical distance any single value sits from the mean — the bigger the number, the more spread out the data.

Range is the simplest but weakest — just highest minus lowest, so one extreme value skews it badly. IQR ignores the top and bottom quarters, giving a fairer picture of the 'typical' spread. Standard deviation uses every single value, making it the most precise but also the most sensitive to calculate correctly.

Statistics questions can appear under any of the four MYP Mathematics criteria, but they show up most often in Criterion A (Knowing and understanding) for calculations, and Criterion D (Applying mathematics in real-life contexts) when you're asked to interpret spread and centre in a real scenario, not just compute a number.

'Calculate' means show your working to reach a numerical answer. 'Compare' means identify similarities and differences between two data sets, usually centre and spread together. 'Justify' means give valid reasons for your choice of measure. 'Determine' means obtain the answer, usually with some working, showing the relevant steps.

Yes — for schools that opt into the MYP eAssessment in Year 5, on-screen Mathematics papers do include statistics and probability questions, often set in real-world contexts like sport, health data or environmental measurements. Not every MYP school uses the eAssessment, though; many assess this unit entirely through school-based criterion tasks instead.

MYP 4-5 builds the foundation — mean, median, mode, range, IQR and standard deviation by hand and by GDC. DP Maths Analysis & Approaches (AA) and Applications & Interpretation (AI) both assume this is already solid, then add variance formulas, correlation, regression, and — at HL — the chi-squared test and normal distribution.

Use your GDC to check your answer, not to replace the working. Most MYP criteria reward shown method — the formula, the substitution, the steps — even when a calculator's one-variable statistics mode gives you the number instantly. Learn the manual method first; the calculator becomes a time-saver, not a shortcut around understanding.

The students who improve fastest here practise interpreting data, not just calculating it — asking 'why does this measure suit this context?' rather than only reaching for a number. Regular short practice with real data sets (sports statistics, weather data) builds the fluency examiners reward under Criterion D far quicker than repetition alone.

Look for resources that combine short concept explanations with plenty of practice questions and full worked solutions, so your child can check method, not just the final answer. On RevisionPrep, MYP Mathematics Revision Notes and Topical Worksheets cover statistics and probability with exactly this structure, alongside Mock Papers to build exam confidence under timed conditions.