Optimizing imputation strategies for mass spectrometry-based proteomics considering intensity and missing value rates
Bibliographic record
Abstract
Missing values (MVs) in omic datasets affect the power, accuracy, and consistency of statistical and functional analyses. In mass spectrometry (MS)-based proteomics, MVs can arise due to several reasons: peptides could be below instrumental detection limits, peptides or proteins might be absent or depleted from the sample for biological or technical reasons, or data processing could fail to detect a real signal. Several statistical and machine-learning methods have been described for imputing MVs in proteomics, such as Bayesian PCA estimation, random forest, and collaborative filtering. However, these approaches typically do not account for the underlying causes of MVs and treat all missing data uniformly, potentially introducing biases that affect the biological validity of the conclusions drawn from the imputed datasets. We found a strong negative correlation between the proportion of MVs and the average intensity for the individual protein, with more abundant proteins having fewer, but rarely zero, MVs. We divided the peptides from all proteins into nine bins based on their intensities and proportion of MV. Assuming the causes of MVs could be different in different regions, we then investigated the optimal imputation method in each bin, using normalized root mean square error (NRMSE), and found that the optimal imputation method varies across bins. A mix-imputed dataset was assembled using the optimal imputation method from each bin, and it was confirmed to exhibit low deviation from the original unimputed dataset, demonstrating mixing the optimal imputation method from each bin is a reliable strategy.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.022 | 0.035 |
| Meta-epidemiology (narrow) | 0.002 | 0.001 |
| Meta-epidemiology (broad) | 0.003 | 0.003 |
| Bibliometrics | 0.002 | 0.003 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.002 | 0.003 |
| Open science | 0.004 | 0.002 |
| Research integrity | 0.002 | 0.003 |
| Insufficient payload (model declined to judge) | 0.002 | 0.001 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".