Author’s reply: Letter to the Editor: Double counting due to inadequate statistics leads to false-positive findings in “Effects of creatine supplementation on memory in healthy individuals: a systematic review and meta-analysis of randomized controlled trials”
Bibliographic record
Abstract
In their Letter to the Editor, Eckert and Pascher1 correctly identified a flawed statistical analysis that warranted correction pertaining to the increased statistical power of our previous meta-analysis on creatine supplementation and memory performance.2 The inclusion of multiple memory-related outcomes from each study was accompanied with an increased number of the same participants (double counting). This could have altered the outcome estimates in the meta-analyses, indeed leading to an increased risk of false-positive findings. To address this, we have now derived the average effect size for studies presenting multiple memory performance outcomes (expressed as a composite score) through pooled means and standard deviations for each intervention group. After correction, our overall analysis showed that creatine monohydrate does not improve overall memory performance (standardized mean difference [SMD], 0.19; 95% confidence interval [CI], –0.07, 0.46; I2 = 4%; P = 0.15) (Figure 1). Subgroup analyses revealed no differences of creatine monohydrate supplementation with low (≤5 g/day; SMD, 0.25; 95%CI, –0.14, 0.64; I2 = 0%; P = 0.21) or high (>5 g/d; SMD, 0.17; 95%CI, –0.34, 0.69; I2 = 50%; P = 0.51) doses (Figure 2A). However, although young adults (aged 11–31 years) did not benefit from creatine monohydrate (SMD, 0.02; 95%CI, –0.27, 0.31; I2 = 0%, P = 0.90), its effects were prominent in older adults (aged 66–76 years; SMD, 0.80; 95%CI, 0.25–1.34; I2 = 0%; P = 0.004) (Figure 2B), which was the main finding of our previous work.2 Furthermore, no changes were displayed regarding treatment duration (≤2 weeks: SMD, 0.16 [95%CI, –0.23, 0.56], I2 = 33%, P = 0.42; >2 weeks: SMD, 0.30 [95%CI, –0.17, 0.76], I2 = 0%, P = 0.21) (Figure 2C) nor sex (women and men: SMD, 0.18 [95%CI, –0.20, 0.56, I2 = 31%, P = 0.36; women: SMD, 0.42 [95%CI, –0.14, 0.98], I2 = 0%, P = 0.14; men: SMD, –0.11 [95%CI, –1.01, 0.79], P = 0.81) (Figure 2D). Our sensitivity analyses showed no effects of creatine monohydrate on memory performance in nonencapsulated form (SMD, 0.22; 95%CI, –0.08, 0.52; I2 = 16%; P = 0.15) (Figure 3A), normal (SMD, 0.29; 95%CI, –0.09, 0.68; I2 = 35%; P = 0.14) or stressed conditions (SMD, 0.03; 95%CI, –0.46, 0.52; I2 = 0%; P = 0.91) (Figure 3B), and participants lost to follow-up (<15%) (SMD, 0.28; 95%CI, –0.02, 0.59; I2 = 1%; P = 0.07) (Figure 3C).
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 distilled prediction
Teacher imitationNot 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.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.029 | 0.017 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.024 | 0.002 |
| Bibliometrics | 0.001 | 0.002 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
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.
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 teacher head, 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".