Quantify whether the difference between two posterior distributions is consistent with zero difference. Accepts samples from one- or multidimensional posterior distributions. The code returns the p-value that both distributions agree. This can be converted into a number of sigmas, assuming Gaussian statistics.
I recommend you install the package straight from GitHub:
pip install git+https:/SebastianBocquet/PosteriorAgreement
We draw representative samples [x1] and [x2] from P1(x) and P2(x), compute the difference between pairs of points δ ≡ x1 - x2 and construct the probability distribution D from the ensemble [δ]. The probability value (or p-value) then is
where D(0) is the probability of zero difference.
The following figure show the normalized difference distribution, and highlights the are that is integrated to obtain the p-value. This makes sense intuitively: if zero is well within the difference distribution, the p-value is large, indicating good agreement. Conversely, if zero is far from the distribution, the p-value will be very small.
This becomes hard to visualize. But the program is the same: construct the difference distribution D, and compute the p-value using the Equation above.
There are many scenarios where your sample point have non-integer weights. You can pass the weights argument, and we use a modified gaussian kernel density estimator:
https://gist.github.com/tillahoffmann/f844bce2ec264c1c8cb5