At each point information from neighbouring data is used. As the time series considered are finite, the areas at the start and end of the data (especially at higher period bands) will not have all the data required. One solution to make computation possible, chosen here, is to pad the time series with zeros where required. However, the zero padding will impact the reliability of the results. It is standard to use a cone of influence to represent this difference in reliability of results. Pale colours represent those areas outside the cone of influence with less reliable results (as seen on Fig 3). Higher period bands require more data for computation resulting in the cone shape.
Bitcoin’s coherence values appear noticeably less affected by bubble and non-bubble regimes, especially over short and medium terms (2–4, 4–8, 8–16 and 16–32). The non-bubble coherence values are similar to those of the other cryptocurrencies, but the bubble regime values do not reach a similar magnitude to the other cryptocurrencies.

EnergyFinancialsHealthIndustrialsMediaProfessional ServicesRetail & ConsumerTech SectorTelecomsTransportTech
Lettau, M. and S. Ludvigson (2001), “Consumption, aggregate wealth, and expected stock returns”, The Journal of Finance 56 (3), 815–849.