Prior (left) and posterior (right) predictive check for the NPE model. Left: the grey semi-transparent lines represent data generated from the prior predictive distribution, indicating the range of data the model might encounter during training. The red solid line represents the validation data to be inferred by the model, specifically for the measured null. Right: the grey semi-transparent lines represent the posterior predictive samples for each model. The red solid line represents the validation data during the inference.