PreprintCited by 148Single-cell and spatial transcriptomicsGene expression and cancer classificationGenomics and Phylogenetic Studies

Comparison of Transformations for Single-Cell RNA-Seq Data

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Ahlmann-Eltze, Constantin, Huber, Wolfgang·2021·Nature Methods

Abstract

The count table, a numeric matrix of genes × cells, is the basic input data structure in the analysis of single-cell RNA-seq data. A common preprocessing step is to adjust the counts for variable sampling efficiency and to transform them so that the variance is similar across the dynamic range. These steps are intended to make subsequent application of generic statistical methods more palatable. Here, we describe four transformation approaches based on the delta method, model residuals, inferred latent expression state, and factor analysis. We compare their strengths and weaknesses and find that the latter three have appealing theoretical properties. However, in benchmarks using simulated and real-world data, it turns out that a rather simple approach, namely, the logarithm with a pseudo-count followed by principal component analysis, performs as well or better than the more sophisticated alternatives. Software: The R package transformGamPoi implementing the delta method- and residuals-based variance-stabilizing transformations is available via Bioconductor. We provide an interactive website to explore the benchmark results at shiny-portal.embl.de/shinyapps/app/08_single-cell_transformation_benchmark . Contact: constantin.ahlmann@embl.de

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  • The shifted logarithm transformation with size factor s performs well in a benchmark of 22 transformations.

    “The shifted logarithm transformation with size factor s performs well but should not be used with counts per million as an input, as it reflects an unrealistically large overdispersion.”

    From Best practices for single-cell analysis across modalities (2023) · cites this paper as [29]

  • The analytical approximation of Pearson residuals performed similarly well to the shifted logarithm in the benchmark.

    “An approach that was shown to perform similarly well in the aforementioned benchmark29 is the analytical approximation of Pearson residuals”

    From Best practices for single-cell analysis across modalities (2023) · cites this paper as [29]

  • Using counts per million as input with the shifted logarithm transformation reflects unrealistically large overdispersion.

    “The shifted logarithm transformation with size factor s performs well but should not be used with counts per million as an input, as it reflects an unrealistically large overdispersion.”

    From Best practices for single-cell analysis across modalities (2023) · cites this paper as [29]

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Research works printed but not linked: 2

  1. [4]Townes, F. W. Generalized principal component analysis. Preprint at arXiv10.48550/arXiv.1907.02647 (2019).
  2. [45]Ahlmann-Eltze, C. Online supplement of comparison of transformations for single-cell RNA-seq data. Zenodo10.5281/zenodo.7504146 (2022). PMC10172138 37037999

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Authors
Ahlmann-Eltze, C., & Huber, W.
Affiliations
  • Heidelberg University (DE)
  • European Molecular Biology Laboratory (DE)
Corresponding author
Ahlmann-Eltze, Constantin
Venue
Nature Methods
Publisher
openRxiv
Published
2021-06-25
Volume
20
Issue
5
Pages
665-672
ISSN
1548-7091 (ISSN-L)
OpenAlex
W4363673883
Cited by
148
References
55
Citations by year
2026: 40 · 2025: 37 · 2024: 41 · 2023: 19 · 2022: 8 · 2021: 3
FWCI
12.30
Type
journal article
Language
en
Open access
Licence
cc-by
Locations
  • Nature Methods (publishedVersion, cc-by)
  • bioRxiv (Cold Spring Harbor Laboratory) (acceptedVersion, cc-by-nd)
  • PubMed Central (publishedVersion, cc-by)
  • PubMed (publishedVersion)
Funders
  • European Molecular Biology Laboratory
  • Bundesministerium für Bildung und Forschung (031L0263A)
  • H2020 European Research Council (810296)
Topics
  • Life Sciences › Biochemistry, Genetics and Molecular Biology › Molecular Biology › Single-cell and spatial transcriptomics
  • Life Sciences › Biochemistry, Genetics and Molecular Biology › Molecular Biology › Gene expression and cancer classification
  • Life Sciences › Biochemistry, Genetics and Molecular Biology › Molecular Biology › Genomics and Phylogenetic Studies
Keywords
single-cell RNA sequencing, delta method, model residuals, factor analysis, principal component analysis, benchmarking
MeSH terms
Single-Cell Gene Expression Analysis, Software, Sequence Analysis, RNA, Gene Expression Profiling, Single-Cell Analysis

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