A brief post for my first.
Very few people would argue that bitcoin is currently not in a bubble. A simple chart with a logarithmic y-axis highlights the explosive rate of return. A very simple way to find potential bubbles are assets that are increasing at an increasing rate, as BTC currently is.
Perhaps a more interesting way of testing for bubbles is testing for a unit root in a time series. The Augmented Dickey-Fuller (adf) Test, when applied on a rolling basis, has a reasonable success rate in identifying the formation of asset bubbles.
When the p values are high, there is strong evidence that the data is non-stationary - that is, the time series is exhibiting bubble like behaviour. Below, I highlight the current p values on both a 1 year and 3 year rolling basis.
Neither looks particularly promising.