My console predictions were really damn good back in 2014, 120M for PS4 and 60M for XBO, basically nailed both.

oh wow. So the Series estimates seem about on point, but Xbox1 was way undertracked. 51m to 58m.

Those initial few months, yes, but things died off very quickly. By the time the white Xbox One released alongside Sunset Overdrive at the end of 2014, which I had gotten, XOne sales had long tanked and the course was that XOne was already lost and PS4 skyrocketed. The number of must have games were almost nonexistent after the first year, $100 more expensive, forced Kinect, and more of a focus on entertainment than gaming really destroyed the Xbox brand after that first year which led to no more announced console sales shortly thereafter. 

Things really started turning around by the time the One S and especially the One X released. Which around that time was when Game Pass released. 

Phil Spencer had to turn around Xbox’s entire business, including shutting down their entertainment division. It took a few years to get the brand turned around then that’s when they started their studio acquisitions since they had only 3-4 first party studios lol, and focus on PC and Cloud. 

Great numbers! A lot higher for X1 then this site lead us to believe.

It's surprising that the Xbox One lifetime figures would be off by that much. After all, the lion share of the sales came from the USA and the UK where we got numbers every now and then. The bigger European countries weren't mysteries either. And all of this was kept track of year by year, so the Xbox One wasn't a guessing game like Sony's Vita where any kind of sales data was rare outside of Japan.

What are people on InstallBase thinking where the notable discrepancies occured? They may not consider VGC estimates reliable, but ZhugeEX was respected as credible and his estimates weren't too different from what VGC had.

Discrepancies are likely in places there isn't much data that have seen more growth than we originally expected over the last decade. Latin America, Asia, MEA, and Other Europe (mainly Eastern Europe).

Most people gave Xbox One estimates in the low 50M range and I remember seeing one as high as 55M. 

We should get updated 8th gen vs 7th gen article now. They are 175.01M now, vs the 173.22M for the 7th gen.

Considering how close VGC is I wouldn't be surprised if they used VGC as source (they have in the recent past).

This, right here, should hopefully end all of the detractors that keep referencing Ampere numbers suggesting that VGChartz is much less accurate. 

I'd hope that would also quell some of the individuals that suggest this site is biased towards Xbox as well (I see this more from other communities such as N4G). Though, unfortunately, a lot of times when people claim things like that they have their own confirmation bias, so this information may not even be considered by them. 

I mean, considering:
1) PS4 was $100 cheaper at launch.
2) PS4 was more powerful, which meant ALL 3rd party games ran better on it.
3) PS4 had better 3rd party support (I mean, the X1 had almost 0 support from japanese developers).

You gotta wonder why the heck did so many people choose the X1 over the PS4? I'm inclined to think that Xbox's 1st party games did a lot more heavy lifting than Sony's.