[Minor] Analyze: revised sampling

Signed-off-by: oleg komarov <o.komarov11@imperial.ac.uk>
[Minor] Tests: clarity on sampling and betas

Signed-off-by: oleg komarov <o.komarov11@imperial.ac.uk>
[Enhance] Tests: beta quantiles and overlaps

Signed-off-by: oleg komarov <o.komarov11@imperial.ac.uk>