DOI: 10.5281/zenodo.17877420
title: Background data for: Case-control down-sampling in corpus research

description: This dataset records the result of a systematic review on the use of case-control down-sampling in corpus research. It is associated with the following paper:

Sönning, Lukas. 2025. Case-control down-sampling in corpus research. OSF Preprints. https://doi.org/10.31219/osf.io/g74bk_v1

It consists of a UTF-8-encoded, tab-separated data table.

 

Case-control down-sampling

In corpus-based work that (partly) relies on manual coding or disambiguation, the full list of tokens returned by a corpus query is often too large; the researcher is then forced to down-size the initial set of data. This is referred to as down-sampling, and there are various techniques and designs that can be applied (see Sönning 2024). One variant is case-control down-sampling, which uses information about the outcome (or dependent) variable to select a subset of instances from the larger pool. This form of down-sampling can be applied if the outcome variable is categorical (usually binary), and if its realization is readily ascertainable. The prototypical case-control design involves drawing the same number of instances of each level of the categorical response variable. This sampling design is particularly common in epidemiology and health-related sciences.

 

A systematic review of down-sampling practices in corpus research

To better understand how (corpus) linguists down-sample their data, I conducted a systematic review. The report pool includes n = 5,805 research articles published between 2012 and 2024 across 19 linguistic journals. The selection of journals, which are listed in the table below, aims to cover a broad range of subdisciplines and research styles. The following table lists the number of studies in the review by journal; journals are sorted by article count. 

 




Journal
n


Applied Psycholinguistics 
624


Applied Linguistics 
464


World Englishes 
457


Linguistics 
451


Natural Language and Linguistic Theory
425


Language Learning 
408


Studies in Second Language Acquisition 
394


Linguistic Inquiry 
386


English Language and Linguistics
295


Language 
277


Cognitive Linguistics 
255


International Journal of Corpus Linguistics
251


Journal of Sociolinguistics 
224


Corpus Linguistics and Linguistic Theory
190


Language Variation and Change
177


Corpora 
163


English World-Wide
154


Research in Corpus Linguistics
116


International Journal of Learner Corpus Research
94


Total
5,805




 

The database was stored locally and analyzed with the qualitative data analysis software MAXQDA 2022 (Verbi Software 2021). The first step was to identify all studies that used some form of down-sampling. To this end, I searched articles for a number of expressions that may appear in the methods section of relevant papers. The search terms I used are listed next:

 




Search term
Example hit(s)


random[a-z]* sampl[a-z]* 
random sample, randomized samples


random[a-z]* select[a-z]* 
randomly selected, random selection 


a subset of
a subset of


downsampl[a-z]*
downsampled, downsampling


down-sampl[a-z]*
down-sampled, down-sampling


down sampl[a-z]*
down sampled, down sampling


(thinned|thinning)
thinned, thinning


randomization
randomization


oversampling
oversampling


case-control
case-control


stratif[a-z]*
stratified, stratification


random[a-z]* extract[a-z]*
randomly extracted, random extraction


random[a-z]* instances
random instances


random[a-z]* concordances
random concordances


(tokens|cases|concordances) per
tokens per, cases per, concordances per


(a maximum of|at most|up to|no more than) [1-9]{1,}
a maximum of 250, up to 30, no more than 5


(a maximum of|at most|up to|no more than) (two|three|four|five|six|seven|eight|nine|ten|eleven|twelve|twenty|thirty|fourty|fifty)
a maximum of three, up to ten, no more than five




 

This search narrowed down the pool to n = 2,152 articles, which were then screened for whether the study applied down-sampling; n = 236 studies did so. Out of these, n = 25 studies applied a form of case-control down-sampling, and the current dataset concentrates on these 25 research articles. These were coded for the following variables, which correspond to columns in the data table:



article  article ID

doi  DOI for research article

topic  a short summary of the topic of the study

unit_of_analysis  which unit forms the basis of a statistical analysis; can be the individual instances/tokens/concordances returned by the corpus query ("token") or a higher-level unit such as the speaker or text file ("text") or a lexical type or item ("item")

clustering  information about the grouping (or clustering) structure in the data; whether multiple instances/tokens are observed per text file ("text") or lexical type/item ("item"), or both ("text, item")

stratified  whether stratified down-sampling was used ("yes" vs. "no"), which involves drawing separate down-samples from different sub-corpora or other subgroups in the data

strat_by_corpus  whether stratificatied down-sampling involved sampling from different corpora or sub-corpora ("yes" vs. "no"); coded "NA" if no use was made of stratified down-sampling

strat_variable  the variable(s) that was/were used for stratification; coded "NA" if no use was made of stratified down-sampling

structured   whether structured down-sampling was used, which relies on clustering variables (text and/or item) as a stratification variable; "no" indicates that this design feature was not used; if it was used, the clustering variable that informed the selection of instances is given in parentheses ("yes (text)", "yes (item)"); one study applied structured case-control down-sampling ("structured case-control")

unit_of_downsampling  whether down-sampling was executed at the level of the individual instances ("token") or whether higher-level units were targeted for down-sampling ("text", "item")

outcome  the outcome (or dependent) variable in the study

language  the language studied

prop_less_common  proportion of the less common variant (binary outcomes) or least common variant (ternary outcomes)

analysis  statistical procedure used for data analysis: "logistic regression", "recursive partitioning", "naive discriminative learning", "distinctive collexeme analysis", "chi-square tests", "behavioral profiles"

notes  additional notes on study design, data analysis, or interpretation


 

References

Sönning, Lukas. 2024. Down-sampling from hierarchically structured corpus data. International Journal of Corpus Linguistics 29(4). 507–533. doi: 10.1075/ijcl.23079.son

VERBI Software. 2021. MAXQDA 2022 [computer software]. Berlin, Germany: VERBI Software. Available from maxqda.com.