How to compare answers from two AIs using clear criteria
To compare two AI answers, keep the task identical and define what counts as a good result beforehand. Choosing on fluency alone may reward a convincing answer that does not meet your need.
The exercise below evaluates your particular task rather than creating a universal tool ranking. A small comparison does not represent every model, plan or type of use.
1. Use the same input
Give both tools the same goal, reference material and expected format. If one received extra documents or earlier context, record that difference.
Conversation history can change an answer. For a simpler comparison, start with independent requests and explain the necessary context in both.
2. Define three or four criteria
Choose observable aspects relevant to the real task. For a summary, fidelity and coverage may matter more than vocabulary variety.
Anthropic’s evaluation documentation addresses defining success and assessing outcomes. The table below is a simplified editorial example.
| Criterion | Question to answer |
|---|---|
| Fidelity | Were supplied facts preserved? |
| Completeness | Were required items included? |
| Format | Was the requested structure followed? |
| Usefulness | Can you perform the next action? |
Avoid an overall score before considering the criteria. A major information error should not disappear inside an average of cosmetic strengths.
3. Read without the tool name
If possible, label outputs only A and B during the first review. This helps focus the assessment on what was actually delivered.
Record a concrete example of success or failure for each criterion. “I liked it more” can be a legitimate preference, but it does not explain what should improve.
4. Check facts outside the comparison
Agreement between two answers does not turn a claim into truth. Use the original material or a primary source to check information affecting the decision.
Consult the source-checking workflow when numbers, quotations or external links appear.
5. Request an evidence-based review
You can use another automated reading to organize observations. It should point to evidence in the text instead of merely declaring a winner.
Compare answers A and B using the criteria below.
For each criterion, show a relevant passage and explain your assessment.
Distinguish factual error, missing information and style preference.
When there is no basis to judge a fact, mark it as unverified.
Do not choose an answer solely for length or a confident tone.The classification from this review still needs checking. An evaluator can miss a failure or prefer wording without providing an adequate reason.
6. Use the result to improve the task
If both failed at the same point, revisit the instructions or the quality of the supplied material. The comparison may reveal a problem in the request rather than a useful difference between tools.
Keep the input, criteria and observations with your prompt library. That makes the test repeatable later.
Frequently asked questions
Is the longer answer better?
Not necessarily. Check whether it completes the task, preserves facts and uses the required format.
Does agreement between two AIs confirm a fact?
No. Both may repeat the same mistake or rely on insufficient information; check the source.
Can I ask one AI to judge another?
That may help organize a review, but the judgment also needs criteria and does not replace a verifiable reference.