Skip to content

Predictions refer to latent f(x) than y values #101

@micmicqb

Description

@micmicqb

Hey, great effort, would love to see Bayesian approaches be adopted and such workflow tools bridge the practice gap.

A comment on the example. A Logistic Regression model is presented:
\begin{align}
y_i | f_i &\sim \text{Bernoulli}(\text{logit}=f_i), \
f_i | x_i $= w^\top x_i, \
w &\sim \mathcal{N}(0, \sigma^2), \
\sigma &\sim \dots
\end{align}

Method predict_dist seems to sample the posterior $f|D$ instead of $y|D$ (which would be $\in{0, 1}$). This is a bit problematic, as MAP logistic regression already returns a point estimate for $f$, which defines a Bernoulli distribution for $y$. In the Bayesian case, $y|D \sim \text{Bernoulli}(p=\mathbb{E}[f|D])$.

Similarly, predict seems to give the median of $f|D$ (which incidentally is not necessarily a useful quantity in the Bayesian paradigm).

Did I misunderstand function or intent?

Metadata

Metadata

Assignees

No one assigned

    Labels

    No labels
    No labels

    Type

    No type
    No fields configured for issues without a type.

    Projects

    No projects

    Milestone

    No milestone

    Relationships

    None yet

    Development

    No branches or pull requests

    Issue actions