Investigate p-value significance as alternative to correlation to identify intertidal pixels

[robbibt]

Correlation between NDWI and tide height works well for identifying intertidal candidate pixels. However, it can produce noisy and unpredictable results when our data is noisy or sparse through time.

Significance (e.g. p-value) of the relationship between NDWI and tide height could be a more robust alternative to correlation. This is supported by the lag_linregress_3D function in DEA Tools, so could be a trivial change.