Although studies presenting inconclusive or null results may be perceived as unsuccessful, the publication of null data, where results may not support the original hypothesis, is essential to ensure transparency and reproducibility in scientific research. Failure to publish null data can lead to wasted resources and an overreporting of positive results.

In this article we discuss the importance of null data, some of the challenges faced by authors when publishing null results, and how some publishers including Karger are working to ensure that scientific rigour and methodology are prioritised over perceived impact.

Why are null data important?

Scientific research relies on a foundation of high-quality data, and all valid data can be meaningful, whether these data support the hypothesis being tested or not. The sharing of null results can help to avoid pursuing unproductive research avenues and can generate new ideas and directions for future study.

The importance of publishing null data is reflected in the Word Medical Association Declaration of Helsinki (1), which states that; “negative and inconclusive as well as positive results must be published or otherwise made publicly available.” However, there is still hesitation among some authors and editors to publish null studies.

One of the main concerns is that studies that report null data usually attract fewer citations (2). This can be problematic where funding, career progression, and journal impact are determined by citation-based metrics (3). Authors may also find that null data can be harder to publish, particularly where journal editors and reviewers may be more focussed on ‘higher impact’ research (4). A combination of these factors has contributed to a significant publishing bias and overreporting of positive results in the literature (4,5).

Positive reporting bias can have serious repercussions, and failure to publish null data is one of the main contributing factors to the reproducibility crisis facing scientific research (4). For example, as discussed by Bespalov et al. (4), a number of independent studies failed to replicate promising preclinical data showing that the drug bexarotene helped to clear β-amyloid from the brain in a mouse model of Alzheimer’s disease (6). These null data were only published after the initiation of a clinical trial of the drug, the primary results of which eventually also turned out to be negative (7). This example illustrates how the publication of null data could help to prevent inefficiencies in clinical drug development. Indeed, lack of reproducibility is thought to be one of the major contributing factors for reduced success rates in clinical trials, contributing to the high costs associated with drug development (8).

A shift away from citation-based metrics

Although change is slow, and citations still provide an important measure of impact, the primary focus on citation-based metrics is starting to shift. A good example of this shift is the UK-based Research Excellence Framework 2029 (9), which will use broader models for assessing academic research contributions based on factors that include wider engagement and societal impact. Some journals, such as Karger’s Biomedicine Hub, are also committed to ensuring editorial decisions are based on sound methodology and scientific quality rather than expected impact.

In addition to the Declaration of Helsinki mentioned above, the importance of publishing null data has been well represented across industry standard publishing and research guidelines, including the Committee on Publication Ethics (COPE) Best Practice Guidelines for Journal Editors (10,11) as well as the latest CONSORT 2025 guidelines for reporting clinical trials (12,13).

Trial registration, study protocols, and registered reports

In 2015, the World Health Organisation published a statement on the public disclosure of clinical trial results, which identified concerns regarding the selective reporting of trial outcomes based on the ‘positivity’ of the results (14). The latest companion article for the CONSORT 2025 guidelines highlights that trial registration presents one of the best ways of ensuring transparency when reporting clinical trial data (12,13). The article also highlights the importance of publishing study protocols for preventing undeclared changes in trial design and outcomes (12).

The relatively new ‘Registered Report’ format for publishing study protocols further helps to eliminate positive publication bias and is being adopted by many publishers including Karger (15). Registered Reports provide authors with the opportunity to have their study protocol reviewed and published, whilst receiving a conditional guarantee that the corresponding results will be published in the same journal regardless of the outcome, provided the study adheres to the original registered methodology. This design offers an improvement on trial registration alone by reducing the likelihood of authors deciding not to publish null data, and by reducing the risk of reviewer bias. A study by Scheel et al. investigating Registered Reports published in the field of psychiatry found that this new format helps to reduce selective reporting and publication bias (16).

Conclusion

The importance of publishing null results for ensuring transparency and preventing publication bias has long been recognised. Despite this recognition, pressures on both authors and publishers continue to contribute to issues of positive bias and selectivity in published data. Although these pressures are unlikely to disappear soon, many publishers including Karger, are supporting authors by providing new avenues for publication. These initiatives help to ensure that valid data from studies that are of sound scientific quality are published, regardless of whether these data are conclusive.

References:

1. https://www.wma.net/policies-post/wma-declaration-of-helsinki/ (Accessed 29/05/25)
2. Tian D, Hu X, Qian Y, Li J. Exploring the scientific impact of negative results. Journal of Informetrics. 2024 Feb; 18(1)101481 (https://doi.org/10.1016/j.joi.2023.101481)
3. Fanelli D. Do pressures to publish increase scientists’ bias? An empirical support from US States data. PLOS One. 2010 Apr; 5:e10271. (https://doi.org/10.1371/journal.pone.0010271)
4. Bespalov A, Steckler T, Skolnick P. Be positive about negatives–recommendations for the publication of negative (or null) results. European Neuropsychopharmacology. 2019 Dec; 29(12):1312-1320 (https://doi.org/10.1016/j.euroneuro.2019.10.007)
5. Tsilidis KK, Panagiotou OA, Sena ES, Aretouli E et al. Evaluation of Excess Significance Bias in Animal Studies of Neurological Diseases. PLOS Biology. 2013 Jul. (https://doi.org/10.1371/journal.pbio.1001609)
6. Cramer PE, Cirrito JR, Wesson DW, Lee CY et al. ApoE-Directed Therapeutics Rapidly Clear β-Amyloid and Reverse Deficits in AD Mouse Models. Science 2012 Feb; 355 (6075) 1503-1506. (DOI: 10.1126/science.1217697)
7. Cummings JL, Zhong K, Kinney JW, Heaney C et al. Double-blind, placebo-controlled, proof-of-concept trial of bexarotene in moderate Alzheimer’s disease. Alzheimer’s Research & Therapy 2016 Jan; 8 (4) (https://doi.org/10.1186/s13195-016-0173-2)
8. Prinz F, Schlange T, Asadullah K. Believe it or not: how much can we rely on published data on potential drug targets? Nat Rev Drug Discov 2011 Aug; 10, 712 (https://doi.org/10.1038/nrd3439-c1)
9. Research Excellence Framework 2029: https://2029.ref.ac.uk/ (Accessed 29/05/25)
10. Teixeira da Silva A. Negative results: negative perceptions limit their potential for increasing reproducibility. Journal of Negative Results in BioMedicine. 2015; 14:12 (https://doi.org/10.1186/s12952-015-0033-9)
11. https://publicationethics.org/about/what-we-do/our-story/core-practices (Accessed 22/05/25)
12. Hopewell S, Chan A, Collins GS, Hróbjartsson A et al. CONSORT 2025 explanation and elaboration: updated guideline for reporting randomised trials. BMJ. 2025 Apr; 389:e081124 (https://doi.org/10.1136/bmj-2024-081124)
13. Hopewell S, Chan A, Collins GS, Hróbjartsson A et al. CONSORT 2025 statement: updated guideline for reporting randomised trials. BMJ. 2025 Apr; 389:e081123 (https://doi.org/10.1136/bmj-2024-081123)
14. https://www.who.int/news/item/09-04-2015-japan-primary-registries-network (Accessed 24/06/25)
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