Usually it's by segment, but a proper analysis would weight upgrades by length of travel, time of day, plane type, quality of FC, etc.

Let's see the formula for that!

This week for me:

LAX-EWR (752) cleared
EWR-ORD (320) did not clear
ORD-LAX (752) cleared

First time I've missed an upgrade in several months, and I missed it by one.

Traveling on a (N) fare, so not exactly surprising even as a 1K.

on 9/12 i flew SEA-SFO-BWI on an N fare (gold here)

sea-sfo: did not clear, i was #20s in the list, about 30+ overall
sfo-bwi: did not clear, #25 out of 42.

was not surprised with the fact that I did not get upgraded as a Gold, especially on an N fare. But just the shear amount of people on the UG list is astounding.

And yet, somehow, people claim that it's all TOD's and sundry other evils that are keeping them from their upgrades.

Well, they certaintly don't help the cause, I'm sure we can all agree on that

That's certainly true.

I'm not sure if I see the CPUs improving but I just count myself lucky when one goes through every now and then as I'm sitting on Gold for this year. What does frustrate me though is the 'black box' nature of the system. It's as if they give you just enough information to guess what's going on but not enough to let you fully understand.

My latest data point - please excuse the long rambling story:
Wife and I were flying LGA-IAH early morning Sat. I checked us in at T-24 and at T-19 received an email that 1 upgrade had cleared (I'd split the reservation to help with upgrade chances). A quick look at the list showed my wife at #1 on the list with 3 seats still open. At T-12 she had dropped to 4th, now with 2 seats open. I ended up giving her the upgrade seat and taking my spot in the back - but here's the interesting part... As at boarding she was still 4th on the list and 2 seats were still showing as empty then as the doors closed a flight attendant came back and (I'm assuming- noticed the yellow luggage handle) informed a passenger that his upgrade had cleared and moved him up to the front - so there's one seat. The second seat was then given to a United employee in uniform who had been waiting in the galley until everyone was settled. Checking the flight status on the app just before I turned my phone off showed no available seats and my wife had moved up to #3 on the list.
Getting back to my original point about enough info to assume but not enough to understand...
I don't expect many CPUs as Gold and even fewer for 2 seats on a flight but I'd sure love to know just how the f@*k the system works.

Three questions:
How does a 2 pax on a single reservation, split at check-in, end-up 4 'positions' apart on the upgrade list?
If all of this is system driven, how did the 1 additional CPU happen post door closure and not at a final sweep at the gate?
If there were still MP members in an upgrade queue then how did a UA employee score a first class seat ahead of them?

No argument there. But as you and I have noted on many a thread on this, folks new to FT or wanting to rant make others believe ToDs are the only root cause.

Of course - and as much as I am an advocate of bringing nefarious TODs to light, no one with half a brain can ignore the impact of less capacity (thus less F seats), cheaper P-type fares to get into the F cabin more easily, etc.

Personally, my CPU success has decreased since 3/3 from the upper 70% range down to around 50%, even though I'm buying higher priced Y fares than in years past.

I'm flying DEN-CLE Wednesday mid-morning flight on a 738, so 16 F seats available in total. At T-96 there were 10 F seats available, T-72 there were 6 seats and this morning at T-48 they are booked full. I'm on a cheap S fare so I was reasonably sure I wouldn't get the CPU (and I didn't - DEN-CLE is a tough route for me) but the Customers Upgraded to United First� list shows 3 names, so my assumption is that 13 of the F cabin 16 seats were sold, correct?

If that's the case, unless you're on a really high Y fare and either GS or possibly 1K then your chances of getting a CPU are very limited.

You are really at 50% on Y fares? Wow.

Except for last minute purchases, my upgrade percentage is 100% on YBM fares (last minute is hopeless since first is already full).

On lower fares my percentage is about 25%. This percentage is across about 70 domestic segments so far this year.

No, I meant higher priced economy fares

I buy mostly Q, W, some H fares.

OK, guys, explain this one.

I'm a 1K travelling with some family members who are silver elite tomorrow through IAH on a cheapo fare.

The flights looked pretty busy. and I haven't had a lot of luck on Thursday upgrades, so I just split myself off into a separate reservation. I didn't try to do any companion upgrade.

I've checked myself in, and I'm currently 20th on the CPU upgrade list to IAH as shown on mobile.united.com. On my connecting flight, I'm only 12th.

That, of course, is better than my silver elite compatriots. They're in the low 50s on the first flight, and in the high 20s on the second.

Now I'm not terribly surprised I didn't get an upgrade -- as I said, the flights look crowded, and Thursdays aren't great for upgrades into IAH. But that said, how is it possible that I'm 20th on a 737? According to the published rules, there would have to be 19 GS and 1K pax on higher fare tickets in front of me. Right? I don't think that's statistically possible. Are there certain published fares that trump my elite status on the CPU list? There has to be. Right?

Why do you say it is not statistically possible? Thursday is a standard consultant travel day, I have been in the high teen's for hub to hub flights.

The waitlist Y/B Golds & Silvers will also be above you -- never been clear to me if they show on the waitlist.