Author here. We mentioned in the piece that we can't rule out that ChatGPT is racist and that it's possible with a larger sample size. A caveat is that these tests might show evidence of bias if the sample size were increased to, say, 10,000 rather than 1,000. That is, with a larger sample size, the p-value might show that ChatGPT is indeed more biased than random chance. The thing is, we just don’t know from their analysis, and it certainly rules out extreme bias.