IA idea · Statistics & hypothesis testing

Do left-handed tennis players have an advantage?

AI SLAI HLAA HL Solid Also in: Sport, Probability

Research question

Are left-handed players over-represented among top-100 ATP players compared with the general population, and do they win more than expected against right-handers of similar ranking?

Adapt it: change the place, the data or the comparison until the question is yours.

Why it makes a good exploration

Around one in ten people is left-handed, but they seem more common in tennis. Match data with handedness recorded lets you test the “surprise advantage” theory properly.

The mathematics you'll need

Binomial distribution and tests of a proportion
Chi-squared goodness-of-fit
Comparing win rates with an expected value based on ranking
Confidence intervals (HL)

Course labels show where a technique sits; using maths from outside your course is fine if you explain it clearly and say it is new to you.

Where the data comes from

Use Jeff Sackmann's ATP match files, which record each player's hand and ranking.

Jeff Sackmann's tennis data — ATP match results, rankings and serve statistics as CSV (CC BY-NC-SA 4.0; a WTA repository exists too).

Cite every source in a footnote where you use it and in your bibliography. Check the licence of any dataset you download.

A possible outline

State the population rate of left-handedness with a source.
Count left-handers in the top 100 across several years; test against the population rate.
Filter left-vs-right matches and compare wins with ranking-based expectations.
Consider surface and era.
Reflect on the data's licence and definitions (who is counted as left-handed).

Pitfalls that cost marks

Counting the same player in several years as independent data.
Ignoring ranking differences when comparing win rates.
No source for the population rate.

Showing personal engagement

If you play tennis, reflect on facing left-handers.
Compare men's and women's tours (the WTA repository).
Check whether the advantage shrinks at the very top.

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

Taking it further

Fit a logistic regression-style model of win probability against ranking difference and test whether handedness shifts it (explain any new maths).

Turn this idea into your IA

Plan this IAOpens the planner with this question, the maths and data sources filled in. Desmos workspacePlot your data, fit models and keep your graphs with your plan. AI feedback on a draftCriterion-by-criterion feedback with evidence from your own text. Coaching, not rewriting. Examiner reviewPete, a practising IA examiner, reads your draft and talks it through with you (€100).