Did the "Yellowstone" series affect Montana population or Home Prices?

Above we can see that the 4 counties containing the largest cities (blue lines) grew in population significantly more than the rate of the entire USA (orange line)

Average Growth Rates:

USA - 0.67%                                                                                              Yellowstone County (Billings) - 1.10% 

Gallatin County (Bozeman) - 2.99%     Lewis and Clark County (Helena) - 1.17%

Missoula County (Missoula) - 0.81%

Below we can see that median listing price per square feet, grew at a faster rate in Montana cities, than the average in the USA.

Average Growth Rates:

USA - 8.13%   Billings - 9.47%

Bozeman - 14.49% Helena - 12.23%

Missoula - 12.01%

Montana counties had strong growth in the years preceding the TV series release in 2018. The graph shows only one period of strong positive correlation (2019 to 2020). Followed directly by a period of negative correlation (2020 to 2021). There is no clear link between viewership growth and county population in the graph below. The statistical evidence is listed below the graph as well.

It is also important to account for the effects of the covid-19 pandemic, and the release dates of the tv shows.

The covid-19 pandemic saw a huge increase in remote work, which allowed many people to move out of the cities and into less populated areas.

The tv shows were often released in the later months of the year. Viewers who watch the show in November of 2020, might not move to Montana until 2021. It is possible that viewership would (if at all) affect population rates of the following year.

*Home prices are calculated by Median Listing Price Per Square Foot*

Below the graph seems to elude to a positive correlation between home prices in Montana cities, and the growth in viewership of "Yellowstone". However it is important notice that home prices in Montana, follow the same trends of the rest of the USA (shown in orange).

There was no statistical evidence to show a correlation between "Yellowstone" viewership and population growth.

There was no statistical evidence to show a correlation between "Yellowstone" Viewership and Montana home price growth.

There was statistical evidence to show a correlation between "Yellowstone" Viewership and US home price growth

Regression analysis was performed to calculate the relationship between "Yellowstone" viewership and:

The average MT population growth rate,

The average MT population growth rate minus the average US growth rate,

The average MT home price growth rate,

The average MT home price growth rate minus the average US price growth rate

The regression analysis showed P values of ~ 0.42 for both calculations of population growth rates.

Analyzing the difference between MT home prices, and US home prices, showed a P value of .06, which is not statistically significant.

However analyzing only the growth rate for MT home prices, there is a P value of .04, which is statistically significant. 

Now it is important to determine if the relation is causation or correlation. I strongly believe this relationship is correlation.

Adjusting the data to account for the show airing later in the year shows no statistical significance

• Moving the viewership data one year forward resulted in P value of .55

• It is possible someone who purchases a home because of a TV show airing in November, would not purchase that home until at least January the following year

MT home prices are affected by national averages/mortgage rates

• Regional home prices are affected by mortgage rates, in 2020 mortgage rates dropped to historic lows. These rates allowed home buyers to spend more on listing price, and less on interest rates.

With no clear relation between MT population and the "Yellowstone" series, and likely no relation between MT home prices and the TV series. Companies should not include the TV series in any business decisions.