Bias introduced by GMM

[chyalexcheng]

GMM introduces bias to the sampler. Two ways to remedy this.

1. slice sampling

• train gmm
• define the lowest score from the trained gmm on expanded samples as the threshold
• generate samples from a low-discrepancy sequence (which one has the property of not being affected by cutting or truncating?)
• include those higher than the threshold

2. restore the uniform prior before the data assimilation loop

[chyalexcheng]

Slice sampling now works. However, old "low-discrepancy" parameter samples are still sampled by Halton. Need to copy old simulations to new iterations.