Measuring Market Saturation?

[Easton Hill]

TLDR;  "How does a smart, data-driven investor, measure market saturation?"

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Gone are the days of just buying any property, furnishing it with crappy furniture, listing it with iPhone photos, and making a killing! 

I think we all know that STR&VR listings have increased year-over-year in almost every market and by large amounts in others! (my own market of Phoenix has seen an unprecedented increase of 20-25%)

So naturally, you see operators, owners, and managers saying things like "The market is saturated" 

My sincere questions are:

How do you know a market is saturated?

How do you measure saturation? 

What date supports your assertions?

How do you even define the word "saturation?" 

In a saturated market, what should an operator expect from ADR, Occupancy, and Pacing? 

When I hear talk about saturation, it's always "feelings" based rather than data-centric. 

I'm earnestly seeking to be the best real estate investor I can be and I'm certain that making "feelings" based choices will lead to bad investments. 

So I ask - "How does a smart, data-driven investor, measure market saturation?"