Internal Assessment

Turn science IA limitations into useful improvement actions

Explain the effect of a limitation and propose a practical change that would strengthen the investigation.

IBvia study guide4 min readUpdated 03 October 2026DP1 & DP2

Begin with evidence from your own investigation

Read the raw observations, procedure notes and processed results before writing an evaluation. Identify a limitation you can support: changing temperature, an uncertain endpoint, narrow coverage, a sensor ceiling or dependence between observations. A generic list can miss the limitation that most affects the answer.

Write a short chain for each issue: what occurred, how it could influence a measurement or interpretation, and why that matters to the research question. Distinguish an observed problem from a possible limitation that remains uncertain.

State the direction or consequence carefully

Explain whether the issue could shift results, increase variation, obscure a relationship or restrict generalization. Only name a direction when you can justify it. If the direction is unclear, explain the uncertainty instead of inventing a definite effect.

For an illustrative temperature-sensitive measurement, readings collected during a gradual temperature rise may reflect both the intended variable and changing temperature. The effect depends on the system's response. Procedure notes and a temperature record help establish whether that explanation is plausible.

Match the action to the mechanism

Propose a change that interrupts the chain you identified. Monitoring and stabilizing temperature addresses drift more directly than simply repeating the same sequence. A clearer endpoint procedure can reduce judgment variation. A wider feasible range can test whether a relationship continues, while a more representative sampling plan can strengthen coverage.

Explain what the action would change in collection or analysis. 'Be more careful' is difficult to inspect. Specifying a consistent measurement reference, recording it in the method and checking it before each trial creates a practical action.

Compare illustrative limitation-action pairs

These pairs illustrate reasoning. Select only issues that fit your actual investigation, and ask your teacher whether a proposed practical change is safe and feasible.

  • A reference position changes between readings: fix and document the reference, then check it throughout collection; this targets a possible offset.
  • A response is barely above the sensor's resolution: adjust the feasible range or measurement method after a pilot; this targets a weak signal.
  • Many readings share one biological sample: sample additional independent material where feasible; this strengthens representation of variation.
  • A dataset overrepresents one site: restrict the conclusion or redesign the sampling comparison; this targets coverage rather than instrument precision.

Prioritize the improvement with the greatest value

Consider how strongly each limitation affects your conclusion and whether the improvement is realistic. A costly instrument upgrade may matter less than a consistent procedure. More trials can help estimate scatter, but repeated biased measurements can remain biased. Explain the advantage and any trade-off introduced by the proposed change.

For a field investigation, tighter sampling conditions may improve comparability while reducing the range of environments represented. Acknowledge that trade-off instead of describing the redesigned method as flawless.

Keep evaluation connected to the conclusion

Revisit the answer to your research question after evaluating limitations. Qualify a claim if the evidence supports a narrower result than you first proposed. Separate a practical improvement to the current investigation from a new research question for future work. Finish with actions whose purpose a reader can understand, and check the evaluation requirements in your current subject guide before submitting.

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Official references

This is an original practical guide from IBvia. The examples are illustrative; your subject guide, assessment year and school instructions determine the requirements.

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