I use ChatGPT a lot each day for writing and organizing tasks, and summaries/explanations of articles etc.

When dealing with topics I'm familiar with, I've found the hallucinations have dropped substantially in the last few years from GPT2 to GPT3 to GPT4 to 4o, especially when web search is incorporated.

LLMs perform best in this regard when working with existing text that you've fed them (whether via web search or uploaded text/documents). So if you paste the text of a study to start the conversation, it's a pretty safe bet you'll be fine.

If you don't have web search turned on, I'd still avoid treating the chat as a search engine though, because 4o will still get little details wrong here and there, especially for newer or more niche topics that wouldn't be as well-represented in the training data.