Regression is a powerful tool in IB Maths AI, but its predictions are not equally reliable at all points. Many students assume that once a regression line is calculated, it can be trusted indefinitely. IB examiners strongly challenge this assumption, especially when predictions extend further into the future.
The main reason regression predictions become less reliable over time is that regression models are built on past data. They describe relationships that existed within a specific time frame. As time passes, conditions change. External factors such as technology, behaviour, environment, or policy can alter the relationship between variables, making earlier patterns less relevant.
Another issue is that regression assumes consistency in trends. When you predict far beyond the observed data, you are assuming that the same linear relationship will continue unchanged. In reality, many trends slow down, level off, or reverse. IB wants students to recognise that regression captures patterns, not guarantees.
Students also confuse accuracy within the data range with accuracy outside it. Regression predictions tend to be most reliable near the centre of the data set, where information is densest. As you move further away from this region, uncertainty increases. Over time, predictions often drift further from the data used to create the model.
Random variation compounds this problem. Small deviations early on can lead to large differences later. Students often overlook how minor inaccuracies grow when predictions are extended repeatedly. IB expects students to acknowledge this accumulation of uncertainty.
Another reason reliability decreases is that regression ignores unmeasured variables. A relationship that appears strong may depend on hidden factors that change over time. When those factors shift, the regression equation no longer reflects reality.
IB questions often ask students to comment on the reliability of predictions rather than compute them. Students who confidently state long-term predictions without caution usually lose marks. Examiners reward students who use careful language and explain why predictions should be treated cautiously.
The key idea is simple: regression is strongest when used near the data and close in time. The further you move away, the weaker the evidence becomes.
Once students understand this, regression questions become less about numbers and more about judgement — exactly what IB Maths AI is designed to assess.
Frequently Asked Questions
Are regression predictions ever reliable long-term?
Rarely. They become increasingly uncertain as conditions change over time.
Does a strong correlation fix this problem?
No. Even strong correlations can weaken or disappear as circumstances change.
What does IB want in these answers?
Cautious conclusions that explain why reliability decreases over time.
RevisionDojo Call to Action
Regression is about reasoning, not forecasting certainty. RevisionDojo is the best platform for IB Maths AI because it trains students to evaluate predictions critically, explain limitations clearly, and use examiner-approved language. If regression questions feel unpredictable, RevisionDojo helps you think like an analyst instead of a calculator.
