[Artificial Intelligence and Statistics Logo] Artificial Intelligence and Statistics 2021

AISTATS 2021 Reviewer Guidelines

How to review?

The intent of the review process is twofold. First, to identify papers which offer significant contributions to the fields of artificial intelligence and statistics, for attendees and readers. Second, to provide constructive feedback to authors that they can use to improve their work. Your role as a reviewer is critical to both goals. When reviewing a paper, always think about the impact the work may have on the community in the long run—out-of-the-box ideas, novel problems and “bridging fields" contributions are crucial for the successful development of the field so do not neglect high-level picture in favor of technical correctness, which is also important.

Keep in mind: Novel and/or interdisciplinary works (e.g., which are not incremental extensions of previously studied problems but instead perhaps formulate a new problem of interest) are often very easy to criticize, because, for example, the assumptions they make and the models they use are not yet widely accepted by the community (due to novelty). However, such work may be of high importance for the progress of the field in the long run, so please try to be aware of this bias, and avoid dismissive criticism.

This document has two parts:

Acknowledgments: The guidelines and examples of good reviews we use in this document are partially adopted from the NeurIPS 2020 reviewer guidelines, which in turn utilize reviews written for some NeurIPS, ICML, and ICLR papers.

Part 1. Guidelines for writing a good review

The review form will ask you for the following:

1. Summary and contributions: Briefly summarize the paper and its contributions

Summarize the paper motivation, key contributions and achievements in a paragraph.

Although this part of the review may not provide much new information to authors, it is invaluable to ACs, and program chairs, and it can help the authors determine whether there are misunderstandings that need to be addressed in their author response.

There are many examples of contributions that warrant publication at AISTATS. These contributions may be theoretical, methodological, algorithmic, empirical, connecting ideas in disparate fields (“bridge papers"), or providing a critical analysis (e.g., principled justifications of why the community is going after the wrong outcome or using the wrong types of approaches.).

2. Strengths: Describe the strengths of the work. Typical criteria include: soundness of the claims (theoretical grounding, empirical evaluation), significance and novelty of the contribution, and relevance to the AISTATS community.

List the strengths of the submission. For instance, it could be about the soundness of the theoretical claim or the soundness of empirical methodology used to validate an empirical approach. Another important axis is the significance and the novelty of the contributions relative to what has been done already in the literature, and here you may want to cite these relevant prior works. One measure of the significance of a contribution is (your belief about) the level to which researchers or practitioners will make use of or be influenced by the proposed ideas. Solid, technical papers that explore new territory or point out new directions for research are preferable to papers that advance the state of the art, but only incrementally. Finally, a possible strength is the relevance of the line of work for the AISTATS community.

3. Weaknesses: Explain the limitations of this work along the same axes as above.

This is like above, but now focussing on the limitations of this work.

Your comments should be detailed, specific, and polite. Please avoid vague, subjective complaints. Think about the times when you received an unfair, unjustified, short, or dismissive review. Try not to be that reviewer! Always be constructive and help the authors understand your viewpoint, without being dismissive or using inappropriate language. Remember that you are not reviewing your level of interest in the submission, but its scientific contribution to the field!

4. Correctness: Are the claims and method correct? Is the empirical methodology correct?

Explain if there is anything incorrect with the paper. Incorrect claims or methodology are the primary reason for rejection. Be as detailed, specific and polite as possible. Thoroughly motivate your criticism so that authors will understand your point of view and potentially respond to you.

5. Clarity: Is the paper well written?

Rate the clarity of exposition of the paper. Give examples of what parts of the paper need revision to improve clarity.

6. Relation to prior work: Is it clearly discussed how this work differs from previous contributions?

Explain whether the submission is written with the due scholarship, relating the proposed work with the prior work in the literature. The related work section should not just list prior work, but explain how the proposed work differs from prior work appeared in the literature.

Note that authors are excused for not knowing about all non-refereed work (e.g, those appearing on ArXiv). Papers (whether refereed or not) appearing less than two months before the submission deadline are considered contemporaneous to AISTATS submissions; authors are not obligated to make detailed comparisons to such papers (though, especially for the camera ready versions of accepted papers, authors are encouraged to).

7. Reproducibility: Are there enough details to reproduce the major results of this work?

Mark whether the work is not reproducible, some aspects are reproducible, or most aspects are reproducible. Lack of reproducibility should be listed among the weaknesses of the submission.

8. Additional feedback, comments, suggestions for improvement and questions for the authors (Optional)

Add here any additional comment you might have about the submission, including questions and suggestions for improvement.

9. Overall score:

You should NOT assume that you were assigned a representative sample of submissions, nor should you adjust your scores to match the overall conference acceptance rates. The “Overall Score" for each submission should reflect your assessment of the submission's contributions.

10. Confidence score:

11. Does the submission raise potential ethical concerns? This includes methods, applications, or data that create or reinforce unfair bias or that have a primary purpose of harm or injury. If so, please explain briefly.

Yes or No. Note that your rating should be independent of this. Your duty here is to flag papers that might need additional review from the ethical perspective.

12. If you said 'Yes' in 11, please briefly explain the potential ethical concerns.

If the submission might raise any potential ethical concern, please briefly explain the potential concerns.

13. Agree to abide by the AISTATS code of conduct

The AISTATS code of conduct can be found here: AISTATS Code of Conduct

14. Confidential comments for the Area Chair (optional)

If you have comments that you wish to be kept confidential from the authors, you can use the “Confidential Comments to Area Chair" text field. Such comments might include explicit comparisons of the submission to other submissions and criticisms that are more bluntly stated. If you accidentally find out the identities of the authors, please do not divulge the identities to anyone.

Part 2. Examples of Review Content

Contributions: The following are examples of contributions a paper might make. This list is not exhaustive.

“The paper provides a thorough experimental validation of the proposed algorithm, demonstrating much faster runtimes without loss in performance compared to strong baselines."

“The paper proposes an algorithm for [insert] with computational complexity scaling linearly in the observed dimensions; in contrast, existing algorithms scale cubicly."

“The paper presents a method for robustly handling covariate shift in cases where [insert assumptions], and demonstrated the impact on [insert application]."

“The authors provide a framework that unifies [insert field A] and [insert field B], two previously disparate research areas."

“This paper demonstrates how the previously popular approach of [insert] has serious limitations when applied to [insert]."

“The authors propose a new framework for quantifying fairness of ML algorithms."

“The authors show how the definition of fairness in [insert citation] fails to capture [insert], which is a critical example of its failure mode."

Quality: Is the submission technically sound? Are claims well supported by theoretical analysis or experimental results? Is this a complete piece of work or work in progress? Are the authors careful and honest about evaluating both the strengths and weaknesses of their work?

Example from nips30/reviews/1548.html

“The technical content of the paper appears to be correct albeit some small careless mistakes that I believe are typos instead of technical flaw (see #4 below).


4. The equation in line 125 appears to be wrong. Shouldn't there be a line break before the last equal sign, and shouldn't the last expression be equal to E_q[(\frac{p(z,x)}{q(z)})^2]?"

“The idea of having a sandwich bound for the log-marginal likelihood is certainly good. While the authors did demonstrate that the bound does indeed contain the log-marginal likelihood as expected, it is not entirely clear that the sandwich bound will be useful for model selection. This is not demonstrated in the experiment despite being one of the selling point of the paper. It's important to back up this claim using simulated data in experiment."

Example from OpenReview

“Technical issues: The move from (1) to (2) is problematic. Yes it is a lower bound, but by ignoring H(Z), equation (2) ignores the fact that H(Z) will potentially vary more significantly that H(Z|Y). As a result of removing H(Z), the objective (2) encourages Z that are low entropy as the H(Z) term is ignored, doubly so as low entropy Z results in low entropy Z|Y. Yes the -H(X|Z) mitigates against a complete entropy collapse for H(Z), but it still neglects critical terms. In fact one might wonder if this is the reason that semantic noise addition needs to be done anyway, just to push up the entropy of Z to stop it reducing too much. In (3) arbitrary balancing parameters lamda_1 and lambda_2 are introduced ex-nihilo - they were not there in (2). This is not ever justified. Then in (5), a further choice is made by simply adding L_{NLL} to the objective. But in the supervised case, the targets are known and so turn up in H(Z|Y). Hence now H(Z|Y) should be conditioned on the targets. However instead another objective is added again without justification, and the conditional entropy of Z is left disconnected from the data it is to be conditioned on. One might argue the C(X,Y,Z) simply acts as a prior on the networks (and hence implicitly on the weights) that we consider, which is then combined with a likelihood term, but this case is not made. In fact there is no explicit probabilistic or information theoretic motivation for the chosen objective. Given these issues, it is then not too surprising that some further things need to be done, such as semantic noise addition to actually get things working properly. It may be the form of noise addition is a good idea, but given the troublesome objective being used in the first place, it is very hard to draw conclusions. In summary, substantially better theoretical justification of the chosen model is needed, before any reasonable conclusion on the semantic noise modelling can be made."

Clarity: Is the submission clearly written? Is it well organized? (If not, please make constructive suggestions for improving its clarity.) Does it adequately inform the reader? (Note: a superbly written paper provides enough information for an expert reader to reproduce its results.)

Example from /nips30/reviews/1548.html

“While the paper is pretty readable, there is certainly room for improvements in the clarity of the paper. I find paragraphs in section 1 and 2 to be repetitive. It is clear enough from the Introduction that the key advantages of CHIVI are the zero avoiding approximations and the sandwich bound. I don't find it necessary to be stressing that much more in section 2. Other than that, many equations in the paper do not have numbers. The references to the appendices are also wrong (There is no Appendix D or F). There is an extra period in line 188.

The Related Work section is well-written. Good job!"

Example from /nips30/reviews/1173.html

“The paper is generally well-written and structured clearly. The notation could be improved in a couple of places. In the inference model (equations between ll. 82-83), I would suggest adding a frame superscript to clarify that inference is occurring within each frame, e.g. q_{\phi}(z_2^{(n)} | x^{(n)}) and q_{\phi}(z_1^{(n)} | x^{(n)}, z_2^{(n)}). In addition, in Section 3 it was not immediately clear that a frame is defined to itself be a sub-sequence."

Originality: Are the tasks or methods new? Is the work a novel combination of well-known techniques? Is it clear how this work differs from previous contributions? Is related work adequately cited? (For reference, abstracts and links to last year's AISTATS proceedings are available here: http://proceedings.mlr.press/v108/.)

Example from /nips30/reviews/60.html

“The main contribution of this paper is to offer a convergence proof for minimizing sum fi(x) + g(x) where fi(x) is smooth, and g is nonsmooth, in an asynchronous setting. The problem is well-motivated; there is indeed no known proof for this, in my knowledge.


There are two main theoretical results. Theorem 1 gives a convergence rate for proxSAGA, which is incrementally better than a previous result. Theorem 2 gives the rate for an asynchronous setting, which is more groundbreaking."

Example from /nips30/reviews/1173.html

“The paper is missing a related work section and also does not cite several related works, particularly regarding RNN variants with latent variables (Fraccaro et al. 2016; Chung et al. 2017), hierarchical probabilistic generative models (Johnson et al. 2016; Edwards & Storkey 2017) and disentanglement in generative models (Higgins et al. 2017). The proposed graphical model is similar to that of Edwards & Storkey (2017), though the frame-level Seq2Seq makes the proposed method sufficiently original. The study of disentanglement for sequential data is also fairly novel."

Significance: Are the results important? Are others (researchers or practitioners) likely to use the ideas or build on them? Does the submission address a difficult task in a better way than previous work? Does it advance the state of the art in a demonstrable way? Does it provide unique data, unique conclusions about existing data, or a unique theoretical or experimental approach?

Example from /nips30/reviews/688.html

“I liked this article very much. It answers a very natural question: gradient descent is an extremely classical, and very simple algorithm. Although it is known not to be the fastest one in many situations, it is widely used in practice; we need to understand its convergence rate. The proof is also conceptually simple and elegant, and I found its presentation very clear."

Example from /nips30/reviews/3278.html

"This paper seems to be a useful contribution to the literature on protein docking, showing a modest improvement over the state of the art. As such, I think the paper would be well-suited for publication in a molecular biology venue, or perhaps as an application paper at NIPS. The main weakness of the paper in my view is that it is a fairly straightforward application of an existing technique (GCNs) to a new domain (plus some feature engineering). As such I am leaning towards a rejection for NIPS."

Constructive Feedback: Please comment on and take into account the strengths of the submission. It can be tempting to only comment on the weaknesses; however, ACs, and program chairs need to understand both the strengths and the weaknesses in order to make an informed decision. It is useful for the ACs, and program chairs if you include a list of arguments for and against acceptance. If you believe that a submission is out of scope for AISTATS, then please justify this judgement appropriately, including, but not limited to, looking at subject areas and previous AISTATS papers. If you need to cite existing work, please be as precise as possible and give a complete citation.

Example from /nips30/reviews/587.html

“There are several things to like about this paper:

- The problem of safe RL is very important, of great interest to the community and without too much in the way of high quality solutions.

- The authors make good use of the developed tools in model-based control and provide some bridge between developments across sub-fields.

- The simulations support the insight from the main theoretical analysis, and the algorithm seems to outperform its baseline.

However, I found that there were several shortcomings:

Example from OpenReview

“The main contributions of the paper are:

  1. Distributed variant of K-FAC that is efficient for optimizing deep neural networks. The authors mitigate the computational bottlenecks of the method (second order statistic computation and Fisher Block inverses) by asynchronous updating.
  2. The authors propose a “doubly-factored" Kronecker approximation for layers whose inputs are too large to be handled by the standard Kronecker-factored approximation. They also present (Appendix A) a cheaper Kronecker factored approximation for convolutional layers.
  3. Empirically illustrate the performance of the method, and show:
    • Asynchronous Fisher Block inversions do not adversely affect the performance of the method (CIFAR-10)
    • K-FAC is faster than Synchronous SGD (with and without BN, and with momentum) (ImageNet)
    • Doubly-factored K-FAC method does not deteriorate the performance of the method (ImageNet and ResNet)
    • Favorable scaling properties of K-FAC with mini-batch size



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