Turney (1995) argued that a good learner should produce essentially the same concept when trained on two independent samples from the same distribution. Stability here means agreement: train two models on disjoint samples and count how often they give the same label on new data. The machine-learning literature calls the opposite quantity prediction churn.
Dropout-Consistency Training (DCT) tries to build stability into one model. Each minibatch is run through the network n times, each time with a different random dropout mask, and the loss penalizes the n predictions for disagreeing:
def dct_loss(model, x, y, n_passes=5, lam=1.5):
logits = [model(x) for _ in range(n_passes)] # dropout on
ce = mean(cross_entropy(z, y) for z in logits)
penalty = mean(mse(softmax(z_i), softmax(z_j)) for i < j)
return ce + lam * penaltyThe loss is old (Bachman et al. 2014; fraternal dropout, Zolna et al. 2018; R-Drop, Liang et al. 2021). None of those papers measure cross-sample agreement, and the churn papers never test dropout consistency. So this repo asks the one open question: is DCT a good way to buy cross-sample stability, and is it better than the one-line alternatives, raising the dropout rate or the weight decay, at equal accuracy? It answers in three steps: a formalization that says what to expect, a linear simulation where the formalization is exact, and an MLP experiment on five small tabular datasets with a full regularization frontier.
Bottom line. No. DCT is a reweighted dropout penalty, and it behaves like one. In the linear simulation DCT with λ=5 lands on the same accuracy–agreement curve as plain dropout at rate q≈0.7, within 0.1 points. In the MLP experiment DCT raises agreement by at most 1.3 points, and a single-pass model with weight decay 10 beats it by 2 to 3 points at the same accuracy on three of five datasets (ties on the other two). What DCT does remove is seed variance (two seeds on the same data agree 2 to 3 points more), not the variance that comes from drawing a new sample. It costs five forward passes per step for that. If you want one model that agrees more with its own retrains, raise the weight decay; if you can afford five models, average five seeds.
Paired change against standard (dropout 0.3, early stopping), mean over 50 trials and five datasets, in points. Full per-dataset numbers are in Table 1; the frontier comparison in Table 2.
| Method | Train / predict cost | Δ accuracy | Δ agreement | vs single-pass frontier at equal accuracy |
|---|---|---|---|---|
wd=5, wd=10 (weight decay) |
1× / 1× | +1.0, +0.7 | +1.1, +1.6 | define it |
dropout=0.5 |
1× / 1× | −0.3 | +0.0 | part of the sweep; below wd=10 everywhere |
DCT lam=5 |
5× / 1× | +0.3 | +0.4 | −0.1 to −2.8 |
seed-ens-5 |
5× / 5× | +1.0 | +1.9 | +1.7 to −1.4 |
bagging-5 |
5× / 5× | −0.2 | +0.4 | −0.1 to −2.6 |
- One model, no extra compute: weight decay, 5 to 10. Both settings raise accuracy and agreement on every dataset, and every other single-model method sits below them at matched accuracy. Beyond 10 the model collapses.
- Five models at prediction time: average five seeds. It is the only arm that beats the frontier anywhere (High Dim, +1.7 ± 0.7), and it reduces both seed and sample disagreement. Bagging on these sample sizes does little; Breiman (1996) predicts that for a learner this stable.
- DCT's niche is narrow: one model at prediction time, and you specifically want two seeds on the same data to agree. Even there,
wd=10does as much (Table 3).
Write S for a training sample, f_S(x) for the predicted probability of class 1, and ŷ_S(x) for the hard label.
- Disagreement is a variance. Let π(x) be the share of training samples whose model says class 1 at x. Two independent models agree at x with probability π² + (1−π)², so disagreement is 2·E_x[π(x)(1−π(x))]: twice the variance of the hard vote across samples. Exact, with no model assumptions. The experiment measures π(x) directly from the ~30 models that see each test point.
- Hard agreement cannot be bought by flattening. Any monotone rescaling of f−½ (a temperature, a uniform shrink toward ½) leaves every hard label unchanged, so it leaves agreement unchanged. It does move soft metrics like exp(−symmetric KL), which is why the earlier version of this study, which used that metric, saw large "stability" gains from under-confidence.
results/temperature.csvshows hard agreement identical at T = 0.5, 1, 2 while the soft metric moves from 0.70 to 0.95. - In a linear model, DCT is dropout's own penalty with a different weighting. With input dropout at rate q and the usual 1/(1−q) rescaling, the logit's variance across masks is q/(1−q)·Σⱼ wⱼ²xⱼ². The pairwise MSE of n predictions equals twice their variance for every n ≥ 2 (so n changes only gradient noise), and by the delta method Var(p) ≈ [p(1−p)]²·Var(logit). So the DCT penalty is 2λ·q/(1−q)·E_x[(p(1−p))²·Σⱼ wⱼ²xⱼ²], while dropout's own implicit regularizer (Wager, Wang & Liang 2013) is ½·q/(1−q)·E_x[p(1−p)·Σⱼ wⱼ²xⱼ²]. Same object, two differences: DCT's weight is [p(1−p)]² instead of p(1−p), so it acts only near the decision boundary and switches off on confident points; and its coefficient is 4λ·p(1−p) times dropout's, which at λ=5 and typical p(1−p) of 0.1 to 0.25 is 2 to 5×. That predicts DCT λ=5 at q=0.3 ≈ plain dropout at q between 0.55 and 0.7, a pre-registered test. For deep nets, Wei, Kakade & Ma (2020) derive the analogous explicit dropout regularizer, q/(1−q)·Σ_h (a_h ∂f/∂a_h)², and show it reproduces most of dropout's effect.
- The penalty does not point at sample variance. Across-sample variance of a prediction is gᵀΣ_S g, with g the gradient of f with respect to the weights and Σ_S the covariance of trained weights across samples. Mask variance is gᵀΣ_m g, where Σ_m is the covariance dropout induces on the weights: block-diagonal by unit, rank one per unit, proportional to the weights themselves, and independent of the data. DCT penalizes variance under Σ_m. It lowers Σ_S only indirectly, by shrinking whatever it penalizes. This is the formal version of the ACT repo's observation that dropout noise "carries no information about the data": an augmentation penalty uses directions along which the truth is known to be flat; Σ_m has no such property.
- Hypothesis: DCT reduces seed variance, not sample variance. Mask-insensitivity makes the fit less sensitive to initialization and batch order. Turney's target is the sample component. Tested by training an extra seed on the same half.
- Agreement at fixed accuracy is bought with overconfidence. Jiang, Nagarajan, Baek & Kolter (2022): if the vote ensemble over retrains is calibrated, expected disagreement equals expected test error. So a method that raises agreement without raising accuracy must make the vote ensemble more confident than its accuracy warrants.
The rungs of the ladder, by how directly each attacks sample variance: (1) more data; (2) shrinkage, which includes weight decay, the dropout rate, early stopping and DCT; (3) averaging seeds, which removes seed variance only; (4) bagging, which approximates the across-sample average inside one sample; (5) anchoring to a previous model by distillation (Jiang et al. 2022), a different target and out of scope. DCT is rung 2.
- Linear simulation (
linear_sim.py). x ~ N(0, Σ) in 30 dimensions with eigenvalues 1/k; the true coefficient lies on the five largest eigendirections (shrinkage removes noise and keeps signal) or the five smallest (shrinkage eats the signal). Bayes accuracy 80%. Each of 50 trials draws two disjoint halves of n = 100 or 300 and a 2,000-point test set. Sweeps: ridge over C; dropout via Wager et al.'s closed-form penalty over q; DCT over λ at q = 0.3 in closed form and with sampled masks (5 passes, and 2 passes at λ=5); bagging-5. Deterministic arms are fit by L-BFGS, so the comparison is between penalties, not optimizers. - MLP experiment (
experiment.py). Five datasets: three syntheticmake_classificationproblems (High Noise, Small Sample, High Dim), Breast Cancer, and 3,000 rows of UCI Adult. Per trial, 30% is held out as a test set and the rest is split into two disjoint halves; each half keeps a fifth for early stopping (patience 5 on validation cross-entropy, up to 100 epochs). Three models per arm: A on half 1, B on half 2 with the same seed, C on half 1 with another seed. (A, B) is the cross-sample pair; (A, C) the seed-only pair. The network is a 2-layer MLP (64 units, ReLU, dropout), AdamW, batch 32. 50 trials, every arm on the same splits. - Arms.
standard(dropout 0.3); dropout 0.1 / 0.5 / 0.7; weight decay 1 / 3 / 5 / 10 / 20 / 30;5 passes(DCT's compute, no penalty); DCT λ = 0.5 / 1.5 / 5 / 15 with 5 passes, and λ=5 with 2 passes;bagging-5andseed-ens-5(five models, probabilities averaged); andstandardon 25 / 50 / 75% of each half, to price agreement in data. The pre-registered primary DCT arm is λ=5, 5 passes. - Metrics.
agree, the share of test points on which the pair gives the same label; Cohen's κ, which is agreement corrected for the pair's label frequencies, so collapsing to the majority class does not count (weight decay 30 does collapse on Adult); accuracy; confidence; the vote-ensemble statistics of point 6; and per-point across-model and mask variances for the mechanism test. - Frontier test. For each target arm, the agreement of the single-pass sweeps (dropout rate and weight decay) is interpolated at the target's accuracy along their upper envelope. The SE is a bootstrap over trials, so it carries the pairing. Pre-registered rule: DCT "beats the frontier" if it is above by more than two SEs on at least three of five datasets.
Table 1. Paired change against standard, two models on disjoint halves. Percentage points, mean ± paired SE over 50 trials; Δ accuracy / Δ agreement.
| Arm | Adult (3k) | Breast Cancer | High Noise | Small Sample | High Dim |
|---|---|---|---|---|---|
dropout=0.5 |
+0.0 ± 0.1 / -0.1 ± 0.2 | +0.1 ± 0.0 / +0.2 ± 0.1 | -0.7 ± 0.3 / -0.3 ± 0.6 | -0.4 ± 0.2 / +0.3 ± 0.3 | -0.5 ± 0.4 / +0.1 ± 0.9 |
dropout=0.7 |
-0.1 ± 0.1 / -0.9 ± 0.4 | +0.2 ± 0.1 / +0.2 ± 0.2 | -2.4 ± 0.5 / -2.8 ± 1.1 | -0.5 ± 0.3 / -0.4 ± 0.6 | -2.3 ± 0.6 / -4.4 ± 1.5 |
wd=3 |
+0.3 ± 0.1 / -0.6 ± 0.2 | +0.3 ± 0.1 / +0.0 ± 0.1 | +1.3 ± 0.3 / +1.7 ± 0.6 | +0.4 ± 0.2 / +0.8 ± 0.4 | +0.7 ± 0.2 / +1.1 ± 0.5 |
wd=10 |
+0.5 ± 0.1 / +1.7 ± 0.2 | +0.3 ± 0.1 / +0.2 ± 0.2 | -0.7 ± 0.4 / +0.5 ± 1.0 | +1.2 ± 0.3 / +3.0 ± 0.7 | +2.2 ± 0.4 / +2.4 ± 0.8 |
5 passes |
-0.2 ± 0.1 / -0.7 ± 0.4 | +0.0 ± 0.1 / +0.2 ± 0.1 | +0.3 ± 0.2 / +0.4 ± 0.4 | +0.0 ± 0.2 / -0.2 ± 0.4 | -0.1 ± 0.2 / -0.1 ± 0.6 |
DCT lam=1.5 |
-0.1 ± 0.1 / -0.7 ± 0.4 | +0.1 ± 0.1 / +0.1 ± 0.1 | +0.3 ± 0.3 / +0.5 ± 0.5 | +0.1 ± 0.1 / +0.3 ± 0.4 | +0.1 ± 0.2 / +0.1 ± 0.5 |
DCT lam=5 |
+0.0 ± 0.1 / -0.8 ± 0.4 | +0.1 ± 0.0 / +0.2 ± 0.1 | +0.9 ± 0.3 / +1.3 ± 0.5 | +0.4 ± 0.2 / +0.9 ± 0.4 | +0.3 ± 0.2 / +0.3 ± 0.6 |
DCT lam=15 |
-1.3 ± 0.2 / -1.9 ± 0.6 | +0.2 ± 0.1 / +0.2 ± 0.1 | +0.5 ± 0.3 / +0.6 ± 0.7 | +0.6 ± 0.3 / +1.6 ± 0.6 | +0.4 ± 0.3 / +0.1 ± 0.8 |
DCT lam=5, 2 passes |
-0.0 ± 0.1 / -0.7 ± 0.3 | +0.1 ± 0.1 / +0.1 ± 0.1 | +0.7 ± 0.3 / +0.5 ± 0.6 | +0.4 ± 0.2 / +1.0 ± 0.4 | +0.3 ± 0.2 / +0.1 ± 0.6 |
bagging-5 |
+0.2 ± 0.1 / +1.8 ± 0.3 | +0.2 ± 0.1 / -0.1 ± 0.2 | -0.9 ± 0.3 / -0.5 ± 0.8 | -0.0 ± 0.3 / +1.0 ± 0.7 | -0.3 ± 0.4 / -0.3 ± 1.3 |
seed-ens-5 |
+0.3 ± 0.1 / +1.0 ± 0.2 | +0.1 ± 0.1 / +0.1 ± 0.1 | +1.9 ± 0.2 / +2.4 ± 0.6 | +0.9 ± 0.2 / +1.7 ± 0.6 | +1.8 ± 0.4 / +4.1 ± 0.9 |
data=50% |
-0.7 ± 0.1 / -1.4 ± 0.4 | -0.7 ± 0.1 / -0.8 ± 0.2 | -8.4 ± 0.6 / -12.4 ± 1.4 | -4.3 ± 0.5 / -6.9 ± 1.1 | -6.5 ± 0.6 / -10.4 ± 2.0 |
Table 2. Agreement relative to the single-pass frontier at the same accuracy. The frontier is the best of the dropout-rate and weight-decay sweeps at each accuracy (upper envelope, linearly interpolated). Points, mean ± bootstrap SE over trials; negative means the frontier does better.
| Arm | Adult (3k) | Breast Cancer | High Noise | Small Sample | High Dim |
|---|---|---|---|---|---|
DCT lam=1.5 |
-2.9 ± 0.5 | -0.3 ± 0.2 | -1.6 ± 0.5 | -2.8 ± 0.5 | -2.2 ± 0.7 |
DCT lam=5 |
-2.8 ± 0.5 | -0.1 ± 0.2 | -0.8 ± 0.5 | -2.2 ± 0.5 | -2.1 ± 0.7 |
DCT lam=15 |
-5.1 ± 0.6 | -0.1 ± 0.2 | -1.5 ± 0.6 | -1.5 ± 0.5 | -2.2 ± 0.7 |
DCT lam=5, 2 passes |
-2.8 ± 0.4 | -0.3 ± 0.2 | -1.6 ± 0.6 | -2.0 ± 0.5 | -2.3 ± 0.7 |
bagging-5 |
-0.1 ± 0.4 | -0.4 ± 0.2 | -2.6 ± 0.7 | -2.0 ± 0.6 | -2.6 ± 1.2 |
seed-ens-5 |
-0.8 ± 0.3 | -0.3 ± 0.2 | more accurate than any frontier point | -1.4 ± 0.4 | +1.7 ± 0.7 |
Table 3. Where the disagreement goes. Change vs standard in disagreement between two seeds on the same half (seed) and between the two halves (sample), in points. standard row: levels.
| Arm | Adult (3k) | Breast Cancer | High Noise | Small Sample | High Dim |
|---|---|---|---|---|---|
standard (levels) |
5.2 seed, 7.8 sample | 1.2 seed, 3.1 sample | 13.5 seed, 25.9 sample | 7.8 seed, 15.2 sample | 20.2 seed, 35.0 sample |
dropout=0.5 |
-0.1 seed, +0.1 sample | -0.0 seed, -0.2 sample | -1.1 seed, +0.3 sample | -0.5 seed, -0.3 sample | -0.5 seed, -0.1 sample |
wd=10 |
-1.9 seed, -1.7 sample | -0.8 seed, -0.2 sample | -1.6 seed, -0.5 sample | -4.5 seed, -3.0 sample | -6.3 seed, -2.4 sample |
DCT lam=5 |
-0.4 seed, +0.8 sample | -0.0 seed, -0.2 sample | -2.4 seed, -1.3 sample | -0.9 seed, -0.9 sample | -3.3 seed, -0.3 sample |
DCT lam=15 |
-1.2 seed, +1.9 sample | -0.1 seed, -0.2 sample | -2.9 seed, -0.6 sample | -2.7 seed, -1.6 sample | -4.3 seed, -0.1 sample |
seed-ens-5 |
-3.1 seed, -1.0 sample | -0.7 seed, -0.1 sample | -7.3 seed, -2.4 sample | -4.5 seed, -1.7 sample | -11.3 seed, -4.1 sample |
bagging-5 |
-1.6 seed, -1.8 sample | -0.2 seed, +0.1 sample | -0.6 seed, +0.5 sample | -0.6 seed, -1.0 sample | -1.9 seed, +0.3 sample |
Table 4. The vote ensemble. Over the ~30 models that saw each test point: pairwise disagreement, mean error, and overconfidence (mean vote share of the majority class minus majority-vote accuracy). Under a calibrated vote ensemble disagreement would equal error (Jiang et al. 2022).
| Arm | Adult (3k) | Breast Cancer | High Noise | Small Sample | High Dim |
|---|---|---|---|---|---|
standard |
7.2 / 16.5 / +10.6 | 2.9 / 3.4 / +0.5 | 22.5 / 28.6 / +8.2 | 14.0 / 18.5 / +5.8 | 31.8 / 34.5 / +5.4 |
wd=10 |
5.6 / 16.0 / +11.6 | 2.3 / 3.0 / +0.8 | 22.1 / 29.3 / +10.2 | 10.7 / 17.3 / +7.3 | 28.9 / 32.2 / +5.3 |
DCT lam=5 |
7.8 / 16.5 / +10.3 | 2.7 / 3.2 / +0.8 | 21.7 / 27.7 / +9.1 | 13.0 / 18.0 / +6.7 | 31.0 / 34.2 / +5.6 |
seed-ens-5 |
6.0 / 16.2 / +11.5 | 2.7 / 3.2 / +0.7 | 19.4 / 26.7 / +10.0 | 12.1 / 17.6 / +6.8 | 27.3 / 32.7 / +9.2 |
Table 5. Linear simulation: DCT λ=5 against the sweeps. Δ agreement at matched accuracy (points ± SE), and the dropout rate whose agreement equals DCT λ=5's, with the accuracy gap between them.
| Scenario, n | vs dropout sweep | vs ridge sweep | equivalent q | accuracy gap |
|---|---|---|---|---|
| bottom, 100 | -14.2 ± 1.6 | -15.9 ± 1.8 | 0.72 | -0.0 |
| bottom, 300 | -20.4 ± 1.1 | -23.5 ± 1.1 | 0.73 | +0.0 |
| top, 100 | +0.1 ± 0.2 | -0.1 ± 0.2 | 0.73 | +0.3 |
| top, 300 | +0.0 ± 0.1 | +0.0 ± 0.1 | 0.69 | +0.0 |
Table 6. Protocol check: fixed 30 epochs, no validation split (the original protocol). Δ accuracy / Δ agreement vs standard, points.
| Arm | Adult (3k) | Breast Cancer | High Noise | Small Sample | High Dim |
|---|---|---|---|---|---|
dropout=0.5 |
+0.6 ± 0.1 / +2.0 ± 0.2 | +0.0 ± 0.1 / +0.4 ± 0.1 | -1.0 ± 0.2 / +1.6 ± 0.4 | +0.1 ± 0.2 / +1.4 ± 0.4 | +0.1 ± 0.2 / +1.2 ± 0.4 |
wd=10 |
+1.3 ± 0.1 / +7.7 ± 0.3 | +0.3 ± 0.1 / +0.9 ± 0.2 | -1.9 ± 0.2 / +2.3 ± 0.6 | -0.2 ± 0.2 / +2.9 ± 0.5 | +1.1 ± 0.3 / +2.4 ± 0.5 |
DCT lam=5 |
+0.6 ± 0.1 / +1.9 ± 0.2 | +0.0 ± 0.1 / -0.0 ± 0.1 | +0.5 ± 0.2 / +2.1 ± 0.4 | +0.5 ± 0.2 / +1.3 ± 0.3 | +0.0 ± 0.2 / +0.9 ± 0.4 |
DCT lam=15 |
+1.0 ± 0.1 / +3.2 ± 0.2 | +0.1 ± 0.1 / +0.3 ± 0.1 | -1.0 ± 0.2 / +1.8 ± 0.6 | +0.2 ± 0.2 / +2.7 ± 0.5 | +0.1 ± 0.3 / +1.8 ± 0.4 |
seed-ens-5 |
+0.4 ± 0.1 / +1.2 ± 0.2 | -0.0 ± 0.1 / +0.0 ± 0.1 | +1.0 ± 0.2 / +2.4 ± 0.4 | +0.5 ± 0.2 / +1.0 ± 0.2 | +0.9 ± 0.2 / +1.9 ± 0.4 |
- Point 3, the mapping: confirmed. In the linear simulation DCT λ=5 reproduces plain dropout at q = 0.69 to 0.73 with an accuracy gap of 0.0 to 0.3 points (Table 5); the forecast was 0.55 to 0.7. The closed-form penalty and the sampled-mask loss agree within 0.3 points everywhere, so the delta-method form is the right description, and 2 passes match 5 passes, so the extra passes buy nothing but a quieter gradient. Every sweep traces the same curve (figure above): when the signal is on the large eigendirections shrinkage helps all of them equally, and when it is on the small ones shrinkage hurts all of them equally. Bagging a linear model changes nothing, as Breiman (1996) says it should.
- The frontier: DCT is dominated. In the MLP experiment DCT λ=5 sits 2.1 to 2.8 points below the single-pass frontier on Adult, Small Sample and High Dim (|t| > 3), 0.8 ± 0.5 below on High Noise, and at the ceiling on Breast Cancer (Table 2). The frontier is weight decay 5 to 10: both raise accuracy and agreement on every dataset, and 20 is already too much (it collapses to the majority class on Adult and loses 20 points on High Noise). Against the dropout sweep alone DCT is a tie or slightly more accurate, which is the earlier finding; the earlier study never tried a weight decay that was large enough to matter with AdamW (the penalty is multiplied by the learning rate, so 0.1 does nothing).
- Point 5, seed vs sample: confirmed. DCT λ=5 cuts seed-only disagreement by 2.4 to 3.3 points on the three noisy datasets but cross-sample disagreement by only 0.3 to 1.3, and on Adult cross-sample disagreement rises by 0.8 while seed disagreement falls (Table 3; mechanism figure, panel a). Weight decay 10 cuts both, by similar amounts. DCT is a seed-variance reducer.
- Point 6, overconfidence: holds in direction, not as an identity. The vote ensemble here is far from calibrated: on Adult, two models disagree on 7% of points but each is wrong on 17%, so the thirty models mostly share their mistakes (bias, not variance). Across arms, each point of agreement gained comes with about half a point of added vote overconfidence (panel b, slope 0.5). The clean "disagreement equals error" identity needs a regime with more variance than bias than these small problems have.
- Point 4, targeting: the penalty acts where the vote is uncertain, and nowhere else. At baseline, mask variance predicts across-sample variance well (Spearman 0.54 to 0.94 on the logit scale), so Σ_m is not useless as a map of where the fit varies. But DCT's variance reduction is negatively correlated with baseline mask variance on four of five datasets (−0.2 to −0.8; panel c), while weight decay's is positively correlated (0.5 to 0.9). That is the [p(1−p)]² weighting from point 3: DCT switches off on confident points, which are exactly where mask variance is largest, and if anything pushes their logits further out. Weight decay shrinks everywhere, including there.
- Price in data. Agreement rises by 1.3 (Adult) to 10 (High Noise) points per doubling of the training data. Weight decay 10 is worth 2.3× the data on Adult and 1.1 to 1.5× elsewhere; DCT λ=5 is worth 1.1× on High Noise and less than 1× on Adult (
results/data_equivalents.csv). - Protocol does not change the ranking. Under the original fixed budget of 30 epochs with no validation split (Table 6), DCT λ=5 gains 0.9 to 2.1 points of agreement and dropout 0.5 gains 1.2 to 2.0, the earlier finding. Weight decay 10 gains 2.3 to 7.7. Early stopping is itself a rung-2 regularizer; with it in place every shrinkage method has less to add, but the order is the same.
- The method is pseudo-ensemble regularization (Bachman, Alsharif & Precup 2014), later fraternal dropout (Zolna et al. 2018) and R-Drop (Liang et al. 2021). Wei, Kakade & Ma (2020) show the explicit mask-variance penalty reproduces most of what dropout does. None measure agreement between models trained on different samples.
- The evaluation is Turney's (1995). Madani, Pennock & Flake (2004) used disjoint-halves agreement as a validation tool. The churn literature (Milani Fard et al. 2016; Bhojanapalli et al. 2021; Jiang et al. 2022) measures agreement across seeds on the same data and reduces it with entropy regularization, co-distillation, ensembles and distillation; it does not test dropout consistency.
- What this study adds is small: a closed form for what DCT penalizes, a tested mapping from λ to an equivalent dropout rate, and the seed/sample decomposition showing which variance it removes.
- The first version used exp(−symmetric KL) as the stability metric and reported gains that came from under-confidence (point 2).
- The second version measured hard agreement but compared DCT with three regularizer settings, none of them a weight decay large enough to act, and called the result "on the frontier". With the frontier filled in, DCT is below it.
- Both trained for a fixed 30 epochs, which confounds the regularizer with how far training got.
- Neither separated seed variance from sample variance, which turns out to be the whole story.
uv sync
make linear # results/linear.csv, about 15 min on 6 cores
make experiment # results/<dataset>.csv and results/preds/, about 40 min
make figures # analysis tables, figures, and the README tables
make ci # black, isort, flake8, pytest
python experiment.py --fixed-epochs 30 --out results/fixed30 runs the original fixed-budget protocol.
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- Bhojanapalli, S. et al. (2021). On the reproducibility of neural network predictions.
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- Jiang, H., Narasimhan, H., Bahri, D., Cotter, A. & Rostamizadeh, A. (2022). Churn reduction via distillation. ICLR.
- Jiang, Y., Nagarajan, V., Baek, C. & Kolter, J. Z. (2022). Assessing generalization of SGD via disagreement. ICLR.
- Liang, X., Wu, L. et al. (2021). R-Drop: regularized dropout for neural networks. NeurIPS.
- Madani, O., Pennock, D. & Flake, G. (2004). Co-validation: using model disagreement to validate classification algorithms. NeurIPS.
- Milani Fard, M. et al. (2016). Launch and iterate: reducing prediction churn. NeurIPS.
- Turney, P. (1995). Bias and the quantification of stability. Machine Learning 20: 23–33.
- Wager, S., Wang, S. & Liang, P. (2013). Dropout training as adaptive regularization. NeurIPS.
- Wei, C., Kakade, S. & Ma, T. (2020). The implicit and explicit regularization effects of dropout. ICML.
- Zolna, K., Arpit, D., Suhubdy, D. & Bengio, Y. (2018). Fraternal dropout. ICLR.


