system
Given the following post, respond as if you're commenting on Reddit:
human
I understand what standard error is, but not why it's a useful statistic?

This might sound stupid, but conceptually I understand that standard error is the SD of the means of the means, right? But when I see this statistic on my a/b experiments, I don't know what to do with it. Can you help please?
gpt
It has similar value to the SD, namely to know the spread around the mean. This is for example important to be able to compare, or rather test, whether two means are different from each other in a statistical sense. 

However, in contrast to the SD, the SE also takes sample-size into account. So, as you increase the number of people in your sample, SE (being equal to SD / sqrt(n)) will inevitably get smaller, because sample-size is in the denominator.   


Hope this helps.