In order to provide a methodology to detect bubbles in time series, Phillips, Wu, and Yu [23] proposed the supremum augmented Dickey-Fuller (SADF) test. This applies a series of right-tailed unit root tests to expanding windows of a time series (with a fixed start date), defined by where r2 is the final data point to be considered in each window, starting at r0 which is a fraction representing the smallest allowed window size and expanding to 1(the complete data set).
However, cryptocurrency experts had warned of several tell-tale signs that it was likely to be a scam.

El Salvador's move to adopt Bitcoin is the first time Bitcoin has been adopted as a legal tender in a sovereign nation.
Turning to the relationships between different cryptocurrencies, significant coherence is observed in the medium and long term between Bitcoin and Litecoin, which it is believed is due to their similarity. It is seen that short term correlations between the cryptocurrencies considered here are dependent again on news items and market wide events. We want your feedback. Do these Subject Areas make sense for this article? Click the target next to the incorrect Subject Area and let us know. Thanks for your help!