I heard this on Fox News Channel a couple of days ago.

Problem:
The preposition “out” is unnecessary here.

Explanation:
I frequently see and hear “separate out” in sentences such as these three:

• “This will separate out the men from the boys.”
• “Can you you separate out the results from the two groups?”
• “Economists can separate out the values of buildings.”

Here is yet another perfectly understandable verb — “separate” — that has become seen by many speakers and writers of American English as requiring the preposition “out” after it. It doesn’t!

Look at the same three example sentences with “out” removed:

• “This will separate the men from the boys.”
• “Can you you separate the results from the two groups?”
• “Economists can separate the values of buildings.”

We do not lose any clarity by removing “out” from each of the original sentences, Instead, we gain clarity because the listeners or readers are not wondering why “out” was added.

Solution:
“… separate [something] …”