I found a blog that offers good explanations in "layman's terms" (of which I am one, hah):
The first link explains what the numbers are actually mean (the Oracle 4 section is towards the bottom of the webpage):
Genealogical Musings: Finally! A Gedmatch Admixture Guide!
"Using 1 population approximation works the same as Single Population Sharing in Oracle, but I’ve noticed the results are sometimes different, so they’re obviously using a slightly different calculation. Reading the results works the same though: they are showing you a list of specific populations you most closely match, with the distant showing you just how closely you match. Again, this is intended for people whose ancestors all come from the same population."
Which in this UID's case means that she most closely matches the Italian Jewish population in the database.
"Using 4 population approximation uses a combination of 4 specific populations you most closely match and lists your top 20 combos. This was designed for people who have 4 grandparents from 4 different places but it can sometimes also work well if most of your ancestry is mainly from 4 different places/populations (because it does not include percentages)."
This is why there will be some odd 4 population results like Grundy County Jane Doe's top result being 2 Yoruban grandparents, 1 Mankena (both West African peoples), and 1 Hungarian (?!) grandparent respectively. Meanwhile, none of her 1 population results are Hungarian. This is likely due to her ancestry being very concentrated among Yoruban and Bantu peoples.
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Note that this UID's 4 population approximation matches are not from 4 different places/populations. With her closest match being 2 Italian Jewish grandparents and 2 Ashkenazi Jewish grandparents, (and her second and third closest matches both have 3 Italian Jewish grandparents!). Based on looking at other UID Oracle 4 population approximation results, it is very unusual for someone's closest 1 population and 4 population approximation results to match up as much as they do for this Jane Doe. For example, Mowry Wetlands Jane Doe's top 1 population result is South Dutch (Irish being her 9th closest), while her top 4 population result is 3 Irish grandparents and 1 Romanian grandparent.
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The second is an analysis of how to interpret results:
Genealogical Musings: An Oracle Analysis
"Firstly, it's important to remember that the results can be very speculative and it's best not to take them very literally. People in neighboring regions simply share too much DNA to always be able to tell them apart with accuracy. That means the more narrowed down the areas are in the result, the more speculative it is. You could be German, for example, and get French results because they are neighboring countries who share a lot of DNA. It doesn't mean you're French, it just means this particular calculator put that French/German shared DNA into French instead of German."
Relevant to Unidentified persons: "If you are adopted and don't know your ancestral background, it's difficult to know which calculators will be more accurate than others. You should definitely still take all this with a grain of salt, but it is fun to examine and compare with what we do know."
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