In general, this is considered a bad estimate if n is less than 30. Above 30, you're dealing in the realm of pretty good estimates. And so the whole focus of this video is when we think about the sampling distribution, which is what we're going to use to generate our interval, instead of assuming that the sampling distribution is normal, like we did in many other videos using the central limit theorem and all of that, we're going to tweak the sampling distribution. We're not going to assume it's a normal distribution, because this is a bad estimate. We're going to assume that it's something called a t distribution. And the t distribution is essentially, the best way to think about it is it's almost engineered. It's almost engineered, so it gives a better estimate of your confidence intervals and all of that when you do have a small sample size.