Standard Error

What:

How can you ever be sure that your data (and in turn calculations) are accurate in Statistics, like when calculating the Parameters of a Distribution? You can’t. So you introduce a Standard Error. That is is a number (a tool really) that lets you know how sure you can be about your result. The formula is:

$SE=\sqrt{\frac{p(1-p)}{n}}$ Where:

• $p$ is the sample proportion
• $n$ is the sample size

Z Scores

Once you get the Standard Error, you can plug it into a normal distribution table (like the one in the Irish Formula and Tables booklet). That is then the confidence you have in your proportion’s success rate / whatever you’re trying to calculate.