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Record W2002725602 · doi:10.1136/ebmh.11.1.3-a

Missing data and the trouble with LOCF

2008· article· en· W2002725602 on OpenAlex

Why this work is in the frame

A frame that forgets how it found something cannot be audited. These are the routes that admitted this work.

affAt least one author lists a Canadian institution in the pinned OpenAlex snapshot.

Bibliographic record

VenueEvidence-Based Mental Health · 2008
Typearticle
Languageen
FieldMathematics
TopicStatistical Methods in Clinical Trials
Canadian institutionsUniversity of Toronto
Fundersnot available
KeywordsMissing dataDrop outSubject (documents)Data collectionStatisticsPsychologyMedicineComputer scienceMathematics

Abstract

fetched live from OpenAlex

Missing data are the bane of all clinical research. With the possible exception of the CAPRIE trial,1 in which the investigators went to extraordinary lengths that enabled them to followup 99.8% of their 19 000 participants over two years, it is highly unusual for a study to end with complete data on all subjects. There are many reasons for this: a person may omit an item on a questionnaire or refuse to complete it entirely; a vial of blood may be dropped or the analyser fail to function one day; or a participant may not appear for his or her appointment. Longitudinal studies (those that follow participants over time) can be subject to all of these mishaps, but now the problem is magnified in that they could happen at each of the assessment sessions; in addition to which, participants may drop out of the study entirely before all the data are collected. Furthermore, the more sophisticated, multivariable statistical techniques that use two or more variables in the same analysis, such as multiple regression or factor analysis, make the problem even worse, in that most of them require complete data for all of the subjects. If a person is missing one variable out of the, say, 10 that are being analysed, then that subject is dropped entirely from the analysis. Simulations have shown that if as little as 10% of the data is missing, as many as 60% of the subjects could be eliminated.2 One consequence of missing data is a loss of statistical power: differences between groups that would be statistically significant may no longer be so because of the reduced sample size. It may appear at first glance that this is a relatively simple problem to remedy—begin with more people to allow for missing data, or recruit more …

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.

Full frame distilled prediction

Teacher imitation

Not calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.

metaresearch head score (Codex)0.007
metaresearch head score (Gemma)0.014
Version: codex-gemma-dda1882f352aValidation status: machine_predicted_unvalidated
Candidate categoriesMetaresearch
Consensus categoriesnone
DomainCandidate signal: none · Consensus signal: none
Study designCandidate signal: Theoretical or conceptual · Consensus signal: none
GenreCandidate signal: Methods · Consensus signal: Methods
Teacher disagreement score0.635
Threshold uncertainty score0.994

Codex and Gemma teacher scores by category

CategoryCodexGemma
Metaresearch0.0070.014
Meta-epidemiology (narrow)0.0000.000
Meta-epidemiology (broad)0.0010.000
Bibliometrics0.0000.000
Science and technology studies0.0010.001
Scholarly communication0.0000.000
Open science0.0000.000
Research integrity0.0000.000
Insufficient payload (model declined to judge)0.0000.000

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.

Opus teacher head0.798
GPT teacher head0.599
Teacher spread0.199 · how far apart the two teachers sit on this one work
Validation statusscore_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from it