Updated 12 October 2026 · By Pete Bromfield, former Head of Maths with IB examining experience

IA idea · Statistics & hypothesis testing

How much is being near a station worth?

AI SLAI HLAA SL Solid Also in: Finance, Geometry & Voronoi

Research question

In [a town], how strongly is the sale price of similar houses related to their walking distance from the nearest railway station, and what is the estimated price change per extra kilometre?

Make it yours, then agree it with your teacher.

Next step: plan this IA free — the planner opens with this question filled in. For feedback on your own draft, the IA package (€39 once) gives you 5 AI feedback credits and every annotated exemplar in full.

Why it makes a good exploration

Estate agents say transport links add value. Using official sale prices and map distances, you can put a number on it — and discover how many other variables get in the way.

The mathematics you'll need

Scatter plots, correlation and linear regression
Interpreting the gradient in context
Spearman's rank for non-linear relationships
Residual analysis to find unusual properties

Modelling the data, step by step

This idea usually needs a straight-line model. See it worked step by step, with a criterion tip at every step: Straight line y = mx + c · Choosing and comparing models.

Model your own data Paste it from Desmos, GeoGebra or a spreadsheet and get the same play-by-play with your numbers. New to modelling? Start with the modelling workflow. Writing it up? The IA modelling planner comments on each paragraph as you draft — it never writes it for you.

The statistics, step by step

Worked with every number shown, with what examiners look for and the common mistakes: Spearman's rank correlation · Pearson's correlation and regression. Then run the same steps on your own data in Analyse my data, or start from the statistics workflow.

Where the data comes from

Take 40+ sales of one property type in one town from the Price Paid Data; measure distances to the station on OpenStreetMap.

HM Land Registry Price Paid Data — Every residential sale in England and Wales since 1995 (Open Government Licence).
OpenStreetMap — Free map with exact coordinates of schools, hospitals, shops and stations; export or read off coordinates.

Real data for this idea

Primary source: HM Land Registry Price Paid Data: Price Paid Data. Download one year's file and filter to one town; use price, date and postcode. Licence: Open Government Licence v3.0 (read the address-data note on the page).
Also useful: OpenStreetMap. Read off coordinates (right-click, “Show address”) or use Export for a small area. Licence: Open Database Licence: credit “© OpenStreetMap contributors”; data you build from it must be shared alike.

OpenStreetMap is under the Open Database Licence: credit “© OpenStreetMap contributors”. Links checked October 2026; we link to the data and never copy it. More free data sets.

A possible outline

Restrict to one property type and a narrow time window.
Measure distances consistently (walking route or straight line — justify).
Fit a regression and interpret the gradient.
Examine residuals for patterns (new builds, schools, flood zones).
Reflect on confounding variables.

Pitfalls that cost marks

Mixing flats and detached houses.
Using straight-line distance without justification.
Treating the gradient as causal.

Showing personal engagement

Choose your own town.
Compare two towns with different commuting patterns.
Estimate the value of your own street's location.

See Criterion C: personal engagement for what examiners look for.

Which course is it for?

Course	Fit	Maths to lean on
AA SL	Good fit	Scatter plots, correlation and linear regression; Interpreting the gradient in context
AA HL	Not a natural fit	The mathematics is mainly from the AI course; at AA HL the exploration would need an AA-level approach (calculus, proof or probability theory) to reach the top of Criterion E.
AI SL	Good fit	Scatter plots, correlation and linear regression; Interpreting the gradient in context
AI HL	Good fit	Scatter plots, correlation and linear regression; Interpreting the gradient in context

Level: Solid. Needs some independent work beyond class examples. See how the IA differs between AA and AI, SL and HL.

How this idea reaches the top bands

Reflection (D)

For this idea, start with the weak points: mixing flats and detached houses; and using straight-line distance without justification. Say how each one affects your answer.

Use of mathematics (E)

SL: scatter plots, correlation and linear regression; interpreting the gradient in context; spearman's rank for non-linear relationships; residual analysis to find unusual properties, each explained in your own words and carried out correctly.

How statistics explorations reach the top bands in general: Statistics & hypothesis testing IA ideas. Guides: A · B · C · D · E · self-grade sheet.

Taking it further

Try a log-price model and compare with the linear one; discuss which gives a more sensible interpretation.

Extending it for HL

Add an HL technique the question genuinely needs: what an HL statistics exploration adds.

See a complete IA, marked

Should I lease or buy my first car? (AI SL) is a complete statistics exploration, marked on every criterion.

Frequently asked questions

Which IB Maths course is this IA idea for?

It works for AI SL, AI HL and AA SL. We rate it Solid: it needs some independent work beyond class examples.

What mathematics does this IA use?

Scatter plots, correlation and linear regression, interpreting the gradient in context, spearman's rank for non-linear relationships and residual analysis to find unusual properties.

Where can I get data for this IA?

Take 40+ sales of one property type in one town from the Price Paid Data; measure distances to the station on OpenStreetMap. Checked sources and tools: HM Land Registry Price Paid Data and OpenStreetMap.

Turn this idea into your IA

The planner opens with “How much is being near a station worth?” filled in: the question, the maths and the data sources.

Plan this IA free

Your plan is kept in this browser. A free account keeps it with your drafts on any device: Join free · Sign in

Also: free IA self-check · A–E checklist (PDF) · have a draft? AI feedback or a review with Pete (€100)

Writing it up: how to write a Maths IA, step by step · structure and format · mistakes that cost marks · IA statistics, step by step