Finding formula per specific category - mean, median, and mode. Bonus - Histogram

So, is there a formula that would calculate the mean, median, and mode per specific Site?

Not that I am aware of. It would take 3 separate formulas.

(thousands of rows in original file)

How many thousands? 2K, 10K ... 100K? It can make a difference.

In the meantime here is my first "run". With the understanding that thousands is 2-3 K

1. Copy / paste the Sites in column R
2. Remove duplicates
3. For the mean this formula in S2 and filled down.
   Formula:

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4. For median (and this is where the volume of data can become an issue). This is an array formula. They are resource hungry and can slow your workbook down. In T2 and filled down.
   Formula:

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5. Array formula issues hold true for mode as well. Additionally some of the data is multi-modal. If you aren’t familiar with array-entered formulas array enter means the formula must be committed from edit mode by simultaneously pressing and holding down Ctrl and Shift while hitting Enter. In U2 filled down and across until you get blanks.
   Formula:

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If the array formulas are too much load for the data you have let me know. There may be a work around. It would likely require some helper columns.

Also I am not clear on what you want as a histogram. Please upload with a hand typed (a few examples) of the layout/returns envisioned.

No. Those are not tiered. They are all equally modal. (actually none of the values are strictly speaking modal)

I am not sure how to explain this well.

A value qualifies as modal only if there are two or more instances of the value. Which ever value occurs the most times is the mode. In the examples there are multiple duration values for the same site. Also in the example(s) there are only single instances of those values. That is among the reasons why there is a +{0,0} introduced in the formula. It forces all values to repeat at least once. In your sample cases there are never more than two repeating values after adding {0,0}. So they all qualify. MODE.MULT returns all of them in an array. If you select just the MODE.MULT(IF($R2=$A$2:$A$26,$O$2:$O$26+{0,0})) part in the formula bar and hit the F9 function key ... in cell U2 ... you will see an array {1626;1619}. ie. there are multiple modes.

The sense of this might be more apparent with any given site having more than one instance of a given duration value.

If you want tiered returns that is a different issue. It begs for additional details (how would you want relative tiers indicated/displayed). It would also require MODE or MODE.MULT nested within other functions. It also exacerbates the array formula load.