What does SDO stand for?

Anyone know what SDO stands for/ITs defined mathematically but wondering what it is in English words. If its mentioned in the chapter I for some reason cannot find it!

https://mixtape.scunning.com/04-potential_outcomes#statistical-inference

Does it refer to Simple Different in Mean Outcomes as in here?
Mixedtape also mentions Simple Different in Means too. But I wonder why it was not referenced before.

That would make a lot of sense… Thank you very much

I realized this book seems to just drop words and terms out of nowhere sometimes, which is a bit frustrating. I wish there was a symbol list and glossary.

Agree. I also feel the same. It’s quite hard especially when you read it on your own. then the book club comes to the rescue! :star_struck: