The argument continues to rage about whether the tech sector is in a "bubble."

The answer is clear:

It isn't.

"Bubbles" are rare, extreme events in which investment activity and valuations temporarily deviate wildly from historical trends — and then crash back down to the trend line in a colossal collapse.

"Booms," meanwhile, are far more common. They also see ever-increasing investment activity and valuations, and they also end in mean-reversion ("busts.") But the magnitude of the dime-a-dozen boom-bust cycle is nothing like the peak and valley that you experience in a bubble.

The chart below clearly illustrates this.

It shows private investment in tech startups year-by-year since 1990:

As you can see, there is one clear and glaring anomaly over this 25-year period: The late 1990s. In hindsight, that was clearly a "bubble," though it actually wasn't so obvious at the time.

The rest of the period is composed of standard cyclicality — booms and busts. These cycles normally last about 10 years. We're about 7 years into the latest one. At some point soon (this year, next year, the following year?) we'll enter the bust.

SEE ALSO:

* BLODGET: This boom will end in a bust

* DEAR SILICON VALLEY: Here's your wake-up call...