Contrast Facades with Two-Factor Subgroup Design

Purpose

This vignette demonstrates the same build_contrast_analysis() facade workflow on a dataset with two factors (e.g. treatment and genotype), yielding four subgroups: C_WT, T_WT, C_KO, T_KO. We define contrasts:

T_C_gv_WT = T_WT - C_WT
T_C_gv_KO = T_KO - C_KO
WT_KO_comp = T_C_gv_WT - T_C_gv_KO

We start from simulated two-factor peptide data, derive a single subgroup factor, and run both protein-input and peptide-input facades with the same contrast specification. See ContrastFacades.Rmd for the one-factor introduction.

Simulate two-factor data and encode subgroups

options(prolfqua.vectorize = TRUE)

dd <- sim_lfq_data_2Factor_config(
  Nprot = 80,
  with_missing = TRUE,
  weight_missing = 1,
  PEPTIDE = TRUE,
  seed = 7
)

cfg_subgroup <- dd$config$clone(deep = TRUE)
data_subgroup <- dd$data |>
  dplyr::mutate(
    Condition = dplyr::recode(Treatment, A = "C", B = "T"),
    Genotype = dplyr::recode(Background, Z = "WT", X = "KO"),
    Subgroup = paste(Condition, Genotype, sep = "_")
  )

cfg_subgroup$factors <- c(Subgroup = "Subgroup")
cfg_subgroup$factor_depth <- 1

lfq_peptide_2f <- LFQData$new(data_subgroup, cfg_subgroup)
lfq_peptide_2f <- lfq_peptide_2f$get_Transformer()$log2()$lfq

lfq_protein_2f <- lfq_peptide_2f$get_Aggregator()$aggregate()

lfq_peptide_2f$config$hierarchy_keys()

## [1] "protein_Id" "peptide_Id"

lfq_protein_2f$config$hierarchy_keys()

## [1] "protein_Id"

lfq_protein_2f$config$nr_children

## [1] "nr_children_protein_Id"

Define contrasts

contrasts_2f <- c(
  T_C_gv_WT = "SubgroupT_WT - SubgroupC_WT",
  T_C_gv_KO = "SubgroupT_KO - SubgroupC_KO",
  WT_KO_comp = "T_C_gv_WT - T_C_gv_KO"
)

Three contrasts: two within-genotype treatment effects and their difference (interaction-like comparison).

Protein-input facades

The following facades require aggregated input. firth is included here because it can be fitted directly on aggregated protein input.

fa_lm_2f <- build_contrast_analysis(
  lfq_protein_2f,
  "~ Subgroup",
  contrasts_2f,
  method = "lm"
)

fa_limma_2f <- build_contrast_analysis(
  lfq_protein_2f,
  "~ Subgroup",
  contrasts_2f,
  method = "limma"
)

fa_limma_impute_2f <- build_contrast_analysis(
  lfq_protein_2f,
  "~ Subgroup",
  contrasts_2f,
  method = "limma_impute"
)

fa_lm_missing_2f <- build_contrast_analysis(
  lfq_protein_2f,
  "~ Subgroup",
  contrasts_2f,
  method = "lm_missing"
)

fa_deqms_2f <- build_contrast_analysis(
  lfq_protein_2f,
  "~ Subgroup",
  contrasts_2f,
  method = "deqms"
)

fa_lm_impute_2f <- build_contrast_analysis(
  lfq_protein_2f,
  "~ Subgroup",
  contrasts_2f,
  method = "lm_impute"
)

fa_firth_protein_2f <- build_contrast_analysis(
  lfq_protein_2f,
  "~ Subgroup",
  contrasts_2f,
  method = "firth"
)

Because all protein-input facades share the same interface and report protein-level contrasts, their outputs can be combined directly.

# Proteins missing in the baseline lm facade (used to flag rescued proteins)
lm_missing_ids_2f <- fa_lm_2f$get_missing() |>
  dplyr::select(protein_Id, contrast) |>
  dplyr::mutate(rescued = TRUE)

results_protein_2f <- bind_rows(
  fa_lm_2f$get_contrasts(),
  fa_limma_2f$get_contrasts(),
  fa_limma_impute_2f$get_contrasts(),
  fa_lm_missing_2f$get_contrasts(),
  fa_lm_impute_2f$get_contrasts(),
  fa_deqms_2f$get_contrasts(),
  fa_firth_protein_2f$get_contrasts()
) |>
  dplyr::select(dplyr::any_of(c(
    "facade", "modelName", "protein_Id", "contrast", "avgAbd", "diff", "FDR",
    "statistic", "std.error", "df", "p.value", "conf.low", "conf.high",
    "sigma"
  ))) |>
  dplyr::left_join(lm_missing_ids_2f, by = c("protein_Id", "contrast")) |>
  dplyr::mutate(
    rescued = dplyr::coalesce(rescued, FALSE),
    significant = FDR < 0.1 & abs(diff) > 0.5
  )

results_protein_2f |>
  dplyr::count(facade, name = "n_results")

## # A tibble: 7 × 2
##   facade       n_results
##   <chr>            <int>
## 1 deqms              232
## 2 firth              240
## 3 limma              232
## 4 limma_impute       240
## 5 lm                 232
## 6 lm_impute          240
## 7 lm_missing         240

For facades that combine several underlying result types, such as lm_missing, the modelName column still tells you where individual rows came from.

results_protein_2f |>
  dplyr::count(facade, contrast, modelName, name = "n_results")

## # A tibble: 24 × 4
##    facade       contrast   modelName      n_results
##    <chr>        <chr>      <chr>              <int>
##  1 deqms        T_C_gv_KO  WaldTest_DEqMS        79
##  2 deqms        T_C_gv_WT  WaldTest_DEqMS        77
##  3 deqms        WT_KO_comp WaldTest_DEqMS        76
##  4 firth        T_C_gv_KO  WaldTestFirth         80
##  5 firth        T_C_gv_WT  WaldTestFirth         80
##  6 firth        WT_KO_comp WaldTestFirth         80
##  7 limma        T_C_gv_KO  limma                 79
##  8 limma        T_C_gv_WT  limma                 77
##  9 limma        WT_KO_comp limma                 76
## 10 limma_impute T_C_gv_KO  limma                 80
## # ℹ 14 more rows

Protein-level volcano comparison

Standard facades

standard_facades_2f <- c("lm", "limma", "deqms")
results_standard_2f <- results_protein_2f |>
  dplyr::filter(facade %in% standard_facades_2f)

ggplot(results_standard_2f, aes(x = diff, y = -log10(p.value), color = significant)) +
  geom_point(alpha = 0.6, size = 1.5) +
  facet_grid(contrast ~ facade, scales = "free_y") +
  geom_vline(xintercept = c(-0.5, 0.5), linetype = "dashed", color = "grey60") +
  geom_hline(yintercept = -log10(0.1), linetype = "dashed", color = "grey60") +
  scale_color_manual(values = c(`TRUE` = "firebrick", `FALSE` = "grey70")) +
  labs(x = "log2 fold change", y = "-log10(p.value)", color = "FDR < 0.1\nand |diff| > 0.5") +
  theme_minimal(base_size = 12)

Volcano plots for the standard protein-level facades (lm, limma, deqms).

Imputation and missingness facades

Rescued proteins (missing in plain lm) are shown as large red diamonds so they stand out clearly. This group includes the LOD imputation facades (lm_missing, lm_impute, limma_impute) and the firth logistic regression facade which models missingness directly.

impute_facades_2f <- c("lm_missing", "lm_impute", "limma_impute", "firth")
results_impute_2f <- results_protein_2f |>
  dplyr::filter(facade %in% impute_facades_2f) |>
  dplyr::mutate(facade = factor(facade, levels = impute_facades_2f))

ggplot(results_impute_2f, aes(x = diff, y = -log10(p.value))) +
  geom_point(data = dplyr::filter(results_impute_2f, !rescued),
             aes(color = significant), alpha = 0.5, size = 1.2) +
  geom_point(data = dplyr::filter(results_impute_2f, rescued),
             color = "red", shape = 18, size = 5, alpha = 1) +
  facet_grid(contrast ~ facade, scales = "free_y") +
  geom_vline(xintercept = c(-0.5, 0.5), linetype = "dashed", color = "grey60") +
  geom_hline(yintercept = -log10(0.1), linetype = "dashed", color = "grey60") +
  scale_color_manual(values = c(`TRUE` = "firebrick", `FALSE` = "grey70")) +
  labs(x = "log2 fold change", y = "-log10(p.value)", color = "FDR < 0.1\nand |diff| > 0.5") +
  theme_minimal(base_size = 12)

Volcano plots for the imputation and missingness facades. Large red diamonds mark proteins rescued (missing in plain lm).

Looking at the strongest protein-level hits

results_protein_2f |>
  dplyr::group_by(facade, contrast) |>
  dplyr::slice_min(order_by = p.value, n = 5, with_ties = FALSE) |>
  dplyr::ungroup() |>
  dplyr::select(facade, contrast, modelName, protein_Id, diff, p.value, FDR)

## # A tibble: 105 × 7
##    facade contrast  modelName      protein_Id    diff  p.value      FDR
##    <chr>  <chr>     <chr>          <chr>        <dbl>    <dbl>    <dbl>
##  1 deqms  T_C_gv_KO WaldTest_DEqMS qc8ZRR~4628  0.628 2.16e-13 1.71e-11
##  2 deqms  T_C_gv_KO WaldTest_DEqMS H7jUye~2322  0.493 2.01e-10 7.94e- 9
##  3 deqms  T_C_gv_KO WaldTest_DEqMS zO74Fn~0389 -0.342 4.69e-10 1.01e- 8
##  4 deqms  T_C_gv_KO WaldTest_DEqMS lRuJ5o~6058  0.542 5.11e-10 1.01e- 8
##  5 deqms  T_C_gv_KO WaldTest_DEqMS uLYRH7~7195  0.588 1.51e- 9 2.35e- 8
##  6 deqms  T_C_gv_WT WaldTest_DEqMS uLYRH7~7195 -0.904 5.36e-11 4.12e- 9
##  7 deqms  T_C_gv_WT WaldTest_DEqMS qc8ZRR~4628  0.420 1.88e-10 7.24e- 9
##  8 deqms  T_C_gv_WT WaldTest_DEqMS HnBvvB~5903  0.335 1.20e- 9 3.07e- 8
##  9 deqms  T_C_gv_WT WaldTest_DEqMS IPV3OT~3010  0.467 2.42e- 9 4.66e- 8
## 10 deqms  T_C_gv_WT WaldTest_DEqMS lCgO3j~8152  0.402 4.22e- 9 6.41e- 8
## # ℹ 95 more rows

Proteins that could not be estimated

Every facade has a get_missing() method that returns the protein x contrast pairs present in the input data but absent from get_contrasts(). This makes it easy to see which proteins each method fails on and to compare coverage.

missing_all_2f <- dplyr::bind_rows(
  fa_lm_2f$get_missing() |> dplyr::mutate(facade = "lm"),
  fa_limma_2f$get_missing() |> dplyr::mutate(facade = "limma"),
  fa_limma_impute_2f$get_missing() |> dplyr::mutate(facade = "limma_impute"),
  fa_lm_missing_2f$get_missing() |> dplyr::mutate(facade = "lm_missing"),
  fa_lm_impute_2f$get_missing() |> dplyr::mutate(facade = "lm_impute"),
  fa_deqms_2f$get_missing() |> dplyr::mutate(facade = "deqms"),
  fa_firth_protein_2f$get_missing() |> dplyr::mutate(facade = "firth")
)

missing_all_2f |>
  dplyr::count(facade, contrast, name = "n_missing") |>
  knitr::kable(caption = "Number of missing protein x contrast pairs per facade")

Number of missing protein x contrast pairs per facade
facade	contrast	n_missing
deqms	T_C_gv_KO	1
deqms	T_C_gv_WT	3
deqms	WT_KO_comp	4
limma	T_C_gv_KO	1
limma	T_C_gv_WT	3
limma	WT_KO_comp	4
lm	T_C_gv_KO	1
lm	T_C_gv_WT	3
lm	WT_KO_comp	4

Per-sample intensities of the missing proteins

missing_proteins_2f <- unique(missing_all_2f$protein_Id)

if (length(missing_proteins_2f) > 0) {
  lfq_protein_2f$data |>
    dplyr::filter(protein_Id %in% missing_proteins_2f) |>
    dplyr::select(protein_Id, sampleName,
                  !!rlang::sym(lfq_protein_2f$config$get_response())) |>
    tidyr::pivot_wider(names_from = sampleName,
                       values_from = !!rlang::sym(lfq_protein_2f$config$get_response())) |>
    knitr::kable(digits = 2, caption = "Per-sample intensities of proteins that could not be estimated")
}

Per-sample intensities of proteins that could not be estimated
protein_Id	A_V3	B_V1	B_V2	B_V3	B_V4	Ctrl_V2	Ctrl_V4	A_V1	A_V2	C_V1	C_V2	C_V3	C_V4	A_V4	Ctrl_V1
hjVK4f~9433	3.88	4.42	4.35	4.28	4.29	3.68	3.86	NA	NA	NA	NA	NA	NA	NA	NA
mVseto~9392	4.47	4.67	4.63	4.66	4.69	NA	NA	4.40	4.50	4.62	4.72	4.54	4.64	NA	NA
QQg7IC~3558	NA	4.34	4.31	4.36	4.31	NA	NA	3.98	NA	4.38	4.31	NA	4.41	3.83	NA
zvzYsk~2881	3.92	NA	NA	NA	NA	4.17	NA	NA	3.79	NA	3.83	NA	3.92	NA	4.18

The missing cells (NA) explain why these proteins cannot be estimated — they lack observations in one or more groups. The lm_missing facade fills in these gaps via group-mean imputation, while lm_impute and limma_impute re-fit after imputing individual values with the LOD and borrowing covariance from successful fits. These should have fewer missing proteins than plain lm or limma.

Estimates for the missing proteins from `lm_missing` and `lm_impute`

For proteins that plain lm could not estimate, the imputation-based facades can still produce contrast results. The table below shows these rescued estimates side by side.

lm_missing_proteins_2f <- fa_lm_2f$get_missing()$protein_Id |> unique()

if (length(lm_missing_proteins_2f) > 0) {
  rescued_2f <- results_protein_2f |>
    dplyr::filter(
      protein_Id %in% lm_missing_proteins_2f,
      facade %in% c("lm_missing", "lm_impute", "limma_impute")
    ) |>
    dplyr::arrange(protein_Id, contrast, facade)

  rescued_2f |>
    knitr::kable(
      digits = 3,
      caption = "Contrast estimates from lm_missing, lm_impute, and limma_impute for proteins that plain lm could not estimate"
    )
} else {
  cat("All proteins were estimable by plain lm — no rescued estimates to show.")
}

Contrast estimates from lm_missing, lm_impute, and limma_impute for proteins that plain lm could not estimate
facade	modelName	protein_Id	contrast	avgAbd	diff	FDR	statistic	std.error	df	p.value	conf.low	conf.high	sigma	rescued	significant
limma_impute	limma	QQg7IC~3558	T_C_gv_KO	4.125	0.411	0.002	5.353	0.077	8.398	0.001	0.235	0.587	0.109	FALSE	FALSE
lm_impute	WaldTest_moderated	QQg7IC~3558	T_C_gv_KO	4.125	0.411	0.001	5.691	0.072	8.653	0.000	0.179	0.644	0.102	FALSE	FALSE
lm_missing	WaldTest_moderated	QQg7IC~3558	T_C_gv_KO	4.118	0.425	0.000	6.660	0.046	9.389	0.000	0.259	0.591	0.074	FALSE	FALSE
limma_impute	limma	QQg7IC~3558	T_C_gv_WT	4.075	0.351	0.005	4.568	0.077	8.398	0.002	0.175	0.526	0.109	TRUE	FALSE
lm_impute	WaldTest_moderated	QQg7IC~3558	T_C_gv_WT	4.075	0.351	0.003	4.856	0.072	8.653	0.001	0.118	0.583	0.102	TRUE	FALSE
lm_missing	groupAverage	QQg7IC~3558	T_C_gv_WT	4.075	0.351	0.001	8.081	0.043	6.000	0.000	0.245	0.457	0.053	TRUE	FALSE
limma_impute	limma	QQg7IC~3558	WT_KO_comp	0.381	-0.060	0.688	-0.556	0.109	8.398	0.593	-0.309	0.188	0.109	TRUE	FALSE
lm_impute	WaldTest_moderated	QQg7IC~3558	WT_KO_comp	0.381	-0.060	0.661	-0.591	0.101	8.653	0.570	-0.293	0.172	0.102	TRUE	FALSE
lm_missing	groupAverage	QQg7IC~3558	WT_KO_comp	0.389	0.000	1.000	0.000	0.043	6.000	1.000	-0.106	0.106	0.053	TRUE	FALSE
limma_impute	limma	hjVK4f~9433	T_C_gv_KO	4.118	0.435	0.003	5.705	0.076	6.398	0.001	0.251	0.620	0.108	FALSE	FALSE
lm_impute	WaldTest_moderated	hjVK4f~9433	T_C_gv_KO	4.118	0.435	0.002	6.015	0.072	6.653	0.001	0.191	0.680	0.102	FALSE	FALSE
lm_missing	WaldTest_moderated	hjVK4f~9433	T_C_gv_KO	4.109	0.452	0.007	4.397	0.095	7.389	0.003	0.237	0.668	0.092	FALSE	FALSE
limma_impute	limma	hjVK4f~9433	T_C_gv_WT	3.900	0.000	1.000	0.000	0.076	6.398	1.000	-0.184	0.184	0.108	TRUE	FALSE
lm_impute	WaldTest_moderated	hjVK4f~9433	T_C_gv_WT	3.900	0.000	1.000	0.000	0.072	6.653	1.000	-0.245	0.245	0.102	TRUE	FALSE
lm_missing	groupAverage	hjVK4f~9433	T_C_gv_WT	3.868	0.000	1.000	0.000	0.069	4.000	1.000	-0.192	0.192	0.085	TRUE	FALSE
limma_impute	limma	hjVK4f~9433	WT_KO_comp	0.218	-0.435	0.015	-4.034	0.108	6.398	0.006	-0.696	-0.175	0.108	TRUE	FALSE
lm_impute	WaldTest_moderated	hjVK4f~9433	WT_KO_comp	0.218	-0.435	0.011	-4.253	0.101	6.653	0.004	-0.680	-0.191	0.102	TRUE	FALSE
lm_missing	groupAverage	hjVK4f~9433	WT_KO_comp	0.252	-0.376	0.012	-5.444	0.069	4.000	0.006	-0.567	-0.184	0.085	TRUE	FALSE
limma_impute	limma	mVseto~9392	T_C_gv_KO	4.519	0.280	0.002	4.803	0.058	10.398	0.001	0.151	0.409	0.109	FALSE	FALSE
lm_impute	WaldTest_moderated	mVseto~9392	T_C_gv_KO	4.519	0.280	0.001	5.133	0.054	10.653	0.000	0.054	0.505	0.102	FALSE	FALSE
lm_missing	WaldTest_moderated	mVseto~9392	T_C_gv_KO	4.559	0.200	0.002	4.469	0.039	11.389	0.001	0.024	0.376	0.080	FALSE	FALSE
limma_impute	limma	mVseto~9392	T_C_gv_WT	4.271	0.742	0.000	11.611	0.064	10.398	0.000	0.600	0.883	0.109	TRUE	TRUE
lm_impute	WaldTest_moderated	mVseto~9392	T_C_gv_WT	4.271	0.742	0.000	11.602	0.064	10.653	0.000	0.516	0.967	0.102	TRUE	TRUE
lm_missing	groupAverage	mVseto~9392	T_C_gv_WT	4.264	0.729	0.000	17.721	0.041	8.000	0.000	0.634	0.823	0.056	TRUE	TRUE
limma_impute	limma	mVseto~9392	WT_KO_comp	0.511	0.462	0.002	5.145	0.090	10.398	0.000	0.263	0.661	0.109	TRUE	FALSE
lm_impute	WaldTest_moderated	mVseto~9392	WT_KO_comp	0.511	0.462	0.001	5.497	0.083	10.653	0.000	0.237	0.687	0.102	TRUE	FALSE
lm_missing	groupAverage	mVseto~9392	WT_KO_comp	0.535	0.387	0.000	9.424	0.041	8.000	0.000	0.293	0.482	0.056	TRUE	FALSE
limma_impute	limma	zvzYsk~2881	T_C_gv_KO	3.902	-0.004	0.982	-0.054	0.072	5.398	0.959	-0.185	0.177	0.107	TRUE	FALSE
lm_impute	WaldTest_moderated	zvzYsk~2881	T_C_gv_KO	3.902	-0.004	0.981	-0.057	0.068	5.653	0.957	-0.259	0.251	0.103	TRUE	FALSE
lm_missing	groupAverage	zvzYsk~2881	T_C_gv_KO	3.889	0.000	1.000	0.000	0.063	3.000	1.000	-0.200	0.200	0.063	TRUE	FALSE
limma_impute	limma	zvzYsk~2881	T_C_gv_WT	3.971	-0.133	0.178	-1.902	0.070	5.398	0.111	-0.310	0.043	0.107	FALSE	FALSE
lm_impute	WaldTest_moderated	zvzYsk~2881	T_C_gv_WT	3.971	-0.133	0.166	-1.938	0.068	5.653	0.104	-0.388	0.121	0.103	FALSE	FALSE
lm_missing	WaldTest_moderated	zvzYsk~2881	T_C_gv_WT	4.018	-0.314	0.017	-3.848	0.066	6.418	0.007	-0.529	-0.099	0.089	FALSE	FALSE
limma_impute	limma	zvzYsk~2881	WT_KO_comp	-0.069	-0.129	0.360	-1.269	0.102	5.398	0.256	-0.386	0.127	0.107	TRUE	FALSE
lm_impute	WaldTest_moderated	zvzYsk~2881	WT_KO_comp	-0.069	-0.129	0.329	-1.331	0.096	5.653	0.234	-0.384	0.125	0.103	TRUE	FALSE
lm_missing	groupAverage	zvzYsk~2881	WT_KO_comp	-0.064	0.000	1.000	0.000	0.063	3.000	1.000	-0.200	0.200	0.063	TRUE	FALSE

Peptide-input facades

The mixed-effects lmer facade and ropeca require lower-level measurements below the analysis subject. The firth facade can also operate directly on peptide-level LFQData. firth is shown a second time here on purpose, because it can also be fitted on peptide input. All three still return protein-level contrasts.

fa_lmer_2f <- build_contrast_analysis(
  lfq_peptide_2f,
  "~ Subgroup + (1 | peptide_Id) + (1 | sampleName)",
  contrasts_2f,
  method = "lmer"
)

fa_ropeca_2f <- build_contrast_analysis(
  lfq_peptide_2f,
  "~ Subgroup",
  contrasts_2f,
  method = "ropeca"
)

fa_firth_peptide_2f <- build_contrast_analysis(
  lfq_peptide_2f,
  "~ Subgroup",
  contrasts_2f,
  method = "firth"
)

results_peptide_2f <- bind_rows(
  fa_lmer_2f$get_contrasts(),
  fa_ropeca_2f$get_contrasts(),
  fa_firth_peptide_2f$get_contrasts()
) |>
  dplyr::select(dplyr::any_of(c(
    "facade", "modelName", "protein_Id", "contrast", "avgAbd", "diff", "FDR",
    "statistic", "std.error", "df", "p.value", "conf.low", "conf.high",
    "sigma"
  ))) |>
  dplyr::mutate(
    significant = FDR < 0.1 & abs(diff) > 0.5
  )

results_peptide_2f |>
  dplyr::count(facade, name = "n_results")

## # A tibble: 3 × 2
##   facade n_results
##   <chr>      <int>
## 1 firth        240
## 2 lmer         179
## 3 ropeca       231

ggplot(results_peptide_2f, aes(x = diff, y = -log10(p.value), color = significant)) +
  geom_point(alpha = 0.6, size = 1.2) +
  facet_grid(contrast ~ facade, scales = "free_y") +
  geom_vline(xintercept = c(-0.5, 0.5), linetype = "dashed", color = "grey60") +
  geom_hline(yintercept = -log10(0.1), linetype = "dashed", color = "grey60") +
  scale_color_manual(values = c(`TRUE` = "firebrick", `FALSE` = "grey70")) +
  labs(
    x = "log2 fold change",
    y = "-log10(p.value)",
    color = "FDR < 0.1\nand |diff| > 0.5"
  ) +
  theme_minimal(base_size = 12)

Volcano plots for the peptide-level facades. Rows are contrasts, columns are backends.

Remarks

The facades make it easy to benchmark alternative contrast backends without rewriting the analysis pipeline:

the protein-level facades now enforce aggregation before modelling
the peptide-level facades now explicitly require lower-level hierarchy below the analysis subject
the shared facade API still makes it straightforward to compare methods once the data level is chosen consistently

The results are comparable at the API level, but the comparison is only meaningful when methods using the same biological unit are plotted together.

Witold E. Wolski

2026-04-02

Purpose

Simulate two-factor data and encode subgroups

Define contrasts

Protein-input facades

Protein-level volcano comparison

Standard facades

Imputation and missingness facades

Looking at the strongest protein-level hits

Proteins that could not be estimated

Per-sample intensities of the missing proteins

Estimates for the missing proteins from `lm_missing` and `lm_impute`

Peptide-input facades

Remarks

Contrast Facades with Two-Factor Subgroup Design

Witold E. Wolski

2026-04-02

Purpose

Simulate two-factor data and encode subgroups

Define contrasts

Protein-input facades

Protein-level volcano comparison

Standard facades

Imputation and missingness facades

Looking at the strongest protein-level hits

Proteins that could not be estimated

Per-sample intensities of the missing proteins

Estimates for the missing proteins from lm_missing and lm_impute

Peptide-input facades

Remarks

Estimates for the missing proteins from `lm_missing` and `lm_impute`