  Structural Bias (SB) is an important type of algorithmic deficiency within
iterative optimisation heuristics. However, methods for detecting structural
bias have not yet fully matured, and recent studies have uncovered many
interesting questions. One of these is the question of how structural bias can
be related to anisotropy. Intuitively, an algorithm that is not isotropic would
be considered structurally biased. However, there have been cases where
algorithms appear to only show SB in some dimensions. As such, we investigate
whether these algorithms actually exhibit anisotropy, and how this impacts the
detection of SB. We find that anisotropy is very rare, and even in cases where
it is present, there are clear tests for SB which do not rely on any
assumptions of isotropy, so we can safely expand the suite of SB tests to
encompass these kinds of deficiencies not found by the original tests.
  We propose several additional testing procedures for SB detection and aim to
motivate further research into the creation of a robust portfolio of tests.
This is crucial since no single test will be able to work effectively with all
types of SB we identify.
