Why does ChatGPT give different answers to the same question?

Because AI assistants generate each answer fresh: they sample words with some randomness, search the web again and pick from the pages they find. A March 2026 study found 34% of repeated ChatGPT answers differed materially. Showing up once and vanishing the next time is normal; measure how often you appear over many runs, not from one screenshot.

Facts

In 10,000 ChatGPT responses (200 queries run 50 times each, February to March 2026), 34% differed materially from the others. (Texta: answer variability study (March 2026))
In that study, variability was 8% at temperature 0.0 and 34% at 0.7, the setting it reports as ChatGPT's default. (Texta: answer variability study (March 2026))
Brands appeared in an average of 72% of repeated runs; top-3 brands in 87% and brands ranked 20th or lower in 43%. (Texta: answer variability study (March 2026))
SE Ranking ran 10,000 keywords through Google's AI Mode three times on June 20, 2025: on average 9.2% of exact URLs overlapped, and 21.2% of keywords shared no URL at all. (SE Ranking: AI Mode research (August 2025))
Ahrefs found ChatGPT cited about half (49.98%) of the URLs it retrieved, in 1.4 million prompts studied in April 2026. (Ahrefs: Why ChatGPT cites one page over another (April 2026))

What makes the answer change?

Several things change between two runs of the same question:

Sampling: the model picks each word with some randomness, so the wording and the names can differ
Search: the assistant searches again and may find different pages
Selection: of the pages it retrieves, it cites only part
Phrasing: a slightly different question changes the recommendations
Context: memory, location, language and the conversation so far

I appeared yesterday and not today. Did I do something wrong?

Probably not. In the Texta data even top-3 brands were missing from about one run in eight, and lower-ranked brands from more than half. One missing answer is noise; a drop over many runs and weeks is a signal.

Does it vary by assistant?

Yes. The same study measured different variability per platform: Claude 28%, ChatGPT 34%, Perplexity 31% and Gemini 38%. Google's AI Mode cited mostly different URLs across same-day runs, though domains repeated a little more often (14.7%) than exact pages.

How do I measure something that changes every time?

Count frequency: run a fixed set of real questions several times in each assistant, in new chats, and record how often you are named. Repeat monthly with the same questions and compare the trend.

easyIndex is the practical answer here: in its monthly scan your coding agent asks ChatGPT, Claude, Perplexity and Gemini your tracked questions and easyIndex records which sources each answer cited, and it measures the effect on your site, which does not vary by run: the visitors who arrive from AI assistants and the AI crawlers that read each page.

Common mistakes

Judging visibility from one screenshot of one answer.
Changing the website after every answer that did not name you.
Asking the question in the same chat again, where earlier answers influence the next one.
Comparing results across different wordings of the question.

How easyIndex solves it

easyIndex measures what stays put while answers move: your coding agent builds the pages over MCP, easyIndex audits each one, checks it live and measures AI visitors and AI crawler reads, and records which sources ChatGPT, Claude, Perplexity and Gemini cite for your tracked questions in the monthly citation scan your agent runs. It costs US$ 30 per website a month, with a 7-day free trial.

Frequently asked questions

Can I make ChatGPT always name my company?

No. No one controls the answer; clear, readable pages raise the chance of being named, they do not fix it.

Is the variation a bug?

No. Generating each answer with some randomness is how these models work by default.

How many runs should I do?

Enough to see a frequency, not a single result; repeat each question several times per assistant.

Do the studies apply to my country?

They used US English queries; check your own questions in your own language.

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Last verified on October 9, 2026.