We've also seen that not only can we calculate the statistic which is trying to estimate this parameter, but we can construct a confidence interval about that statistic based on some confidence level. And so that confidence interval would look something like this. It would be the value of the statistic that we have just calculated, plus or minus some margin of error. And so we'll often say this critical value, z, and this will be based on the number of standard deviations we wanna go above and below that statistic. And so then we'll multiply that times the standard deviation of the sampling distribution for that statistic. Now what we'll see is we often don't know this. To know this, you oftentimes even need to know this parameter.