How do I prompt the API to return me ONLY the probability from 0 a 100 of something?

Example, I am thinking of a solution where I ask the API “, what do you think is the probability that the customer wants to buy the product in the chat. Please return only a number from 0 (least likely) to 100 (most likely)”.

However, the system returns often a larger text…any suggestions?

You can reduce the number of max tokens, this will force the model to end after the set amount of tokens. Keep in mind that GPT is a language model that generates text, it’s not made to perform specific calculations or provide exact probabilities. It is however really good at pretending to do these tasks.

A better approach could be asking a series of binary questions like:

  • “Has the customer shown interest in the product?”
  • “Have they asked any questions about the product?”
  • “Have they mentioned any specific features they are looking for?”
  • “Have they mentioned any concerns or objections to purchasing the product?”

You can then use regular math to determine a probability score based on the number of “yes” responses.

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If you fine tune a base model on buy/not buy, you can use log_probs to give you a number between 0 and 1, and you multiply this by 100 to get your probability.

Admittedly, this is more advanced and would use the API, but totally doable.


That’s a great idea, I didn’t even think about that, you won’t have as much knowledge about how said probability was calculated, but I don’t think it matters in this case.

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Yeah, it works!

Some working details you need to know … you need to convert the token_logprobs to a linear scale before converting it to a percent.

Example: I have a categorizer from Babbage that is trained to output ’ 0’ or ’ 1’. In this example, say ’ 1’ means the lead is going to buy, and ’ 0’ means the lead won’t buy.

"choices": [{"text": " 1", "index": 0, "logprobs": {"tokens": [" 1"], "token_logprobs": [-3.170517e-06], "top_logprobs": [{" One": -13.691312, " 1": -3.170517e-06}], "text_offset": [356]}, "finish_reason": "length"}], "usage": {"prompt_tokens": 124, "completion_tokens": 1, "total_tokens": 125}}'

Then define the base of the natural logarithm:

e = 2.718281828459

Then take the log probs out of the JSON response and convert to linear:

# get the log probability (base e)
LogProb = FullReaction["choices"][0]["logprobs"]["token_logprobs"][0]
print(f"LogProb: {LogProb}")
# convert the log probability to a probability in [0,1]
Prob = e**LogProb

Then multiply the Prob value by 100 to get your percent from the chosen value. So if the value in linear from the chosen value is 0.99 for ' 0', you set the percent to 1-0.99 or 1%. If it is 0.99 for ’ 1’, you set it to 99%. Slight details, but that is all you need.

To get the log_probs info to show up in the response, I believe you just call it out, and since I am making a binary decision on 1-token, here is the core JSON settings to send over:

{"temperature": 0, "max_tokens": 1, "top_p": 1, "logprobs": 2, "frequency_penalty": 0, "presence_penalty": 0}

Not sure why request 2 of them, but I only use the single one from token_logprobs.

Details matter, but this is what you need to do to get it to work.

So in my example, I get

LogProb = -3.170517e-06 for token ' 1' = BUY!
Prob = e**LogProb
# 0.999996829488026

SO the lead has a 99.9996829488026 percent chance of buying. WOOT!