Variable expenses fluctuate based on the business’s usage or output, such as utility bills or raw materials. Fixed production costs, such as rent or salaries, remain constant, regardless of business activity or output. AI technologies will not be accepted as an author(s) of any content submitted to BMJ for publication. BMJ only recognises humans as being capable of authorship since they must be accountable for the work. In addition to being accountable for the parts of the work they have done, an author should be able to identify which co-authors are responsible for specific other parts of the work.

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By adhering to the ICMJE authorship criteria and utilising standardised frameworks like CRediT, researchers can ensure that credit and accountability are properly attributed to research contributions. An authorship statement clarifies the roles and contributions of each researcher in conducted research. It plays a pivotal role in determining the accountability of the research published. Hence, as a researcher striving to establish your reputation, it is important to be well-versed with the ethical guidelines present for authorship. Models 8 to 11 in table S12 show that estimates regarding the incidence of “guest” and “ghost” contributorship differ little between fields. 6, however, junior scientists believe that seniors are advantaged (more guest and fewer ghost contributorships), whereas seniors believe that juniors are advantaged.


  1. Preparation, creation and/or presentation of the published work by those from the original research group, specifically critical review, commentary or revision – including pre- or post-publication stages.
  2. Pay no monthly fees, get payouts up to 7 days earlier, and earn cashback on eligible purchases.
  3. Income is calculated by deducting the total value of the company’s fixed costs during the period from the Contribution Margin.
  4. These biases should be less problematic for our analyses of errors when interpreting author order because these analyses primarily focus on the distribution of contributions for a given author position (for example, Fig. 2).

They will also be expected as individuals to complete conflict-of-interest disclosure forms and provide a summary in the relevant section. In many cases, direct labor is categorized as a fixed expense in the contribution margin income statement format, rather than a variable expense, because this cost does not always change in direct proportion to the amount of revenue generated. Instead, management needs to keep a certain minimum staffing in the production area, which does not vary for lower production volumes.

What are some advantages of contribution margin income statements?

Nonetheless, it is not uncommon to see significant errors in authorship practices in published papers. The purpose of this article is to clarify whose names should be listed as authors on a Plant Cell Reports paper and to give some practical guidelines when writing the authorship contribution statement. The informational value of contribution statements depends not only on their format but also on the process by which they are decided.

Formal analysis

The key difference between gross margin and contribution margin is that fixed production costs are included in the cost of goods sold to calculate the gross margin, whereas they are not included in the same calculation for the contribution margin. This means that the contribution margin income statement is sorted based on the variability of the underlying cost information, rather than by the functional areas or expense categories found in a normal income statement. Given that paper mills are known to buy and sell authorship, and that honorary and gift authorship is also problematic and widespread in science, we, the editors, are increasingly wary of very long author lists and vague authorship contribution statements. It should not be challenging for the editors and peer reviewers to determine if authors meet the criteria for authorship. Also, it should be noted that ChatGPT and other large language models do not fit the criteria for authorship and should also not be listed as authors. Second, public discussions are needed on whether and how contribution disclosures can be standardized.

Note that these and subsequent regressions examine differences in the contributions made by authors listed in different positions and are purely correlational in nature. The objective is to explore the degree to which author position allows observers to infer or “predict” the number or types of authors’ contributions. These regressions are not designed to examine the causal nature of any observed relationships; in particular, we do not seek to determine whether particular contributions “cause” individuals to be placed in particular positions on the byline. Despite their limitations, the contribution measures have key advantages over available alternatives. Most importantly, they allow insights into a large sample of projects, complementing previous qualitative work using small numbers of cases (23).

A statement indicating that “no goods or services were provided in exchange for monies received”, or a similar statement will suffice. Variable expenses are the easier to control of the two types of expenses (variable and fixed). The contribution margin can then be used to determine how well a particular product or segment is performing. Researchers must determine among themselves the precise nature of each person’s contribution, and we encourage open discussion among all participants.

In this example, the article includes an Acknowledgements section and an Author Contributions section. Acquisition of the financial support for the project leading to this publication. Application of statistical, mathematical, computational, or other formal techniques to analyze or synthesize study data. Management activities to annotate (produce metadata), scrub data and maintain research data (including software code, where it is necessary for interpreting the data itself) for initial use and later reuse.

Figure 2A shows that the SD of the contribution count increases with team size for first authors, suggesting more error when estimating the breadth of first authors’ contributions in larger teams. Figure 2B shows the share of teams deviating from the “convention” that first authors have a higher count of contributions than last authors and last authors have a higher count of contributions than middle authors. This share increases from 31.66% in teams of 3 to 57.87% in teams of 14, largely reflecting an increasing likelihood that one of the middle authors made a broader set of contributions than the last author. Overall, author order is less reliable as an indicator of the breadth of authors’ contributions in larger teams. To understand how profitable a business is, many leaders look at profit margin, which measures the total amount by which revenue from sales exceeds costs. But if you want to understand how a specific product contributes to the company’s profit, you need to look at contribution margin, which is the leftover revenue when you deduct the variable cost of delivering a product from the cost of making it.

Figure 2A plots for each author position the SD of individuals’ count of contributions against team size, showing an increase with team size especially for first authors. Figure 2B shows the share of papers deviating from the conventions that first authors have a higher contribution count than last authors and last authors have a higher contribution count than middle authors by team size. Both panels highlight that inferences about the breadth of authors’ contributions based on author position will have a higher error rate in larger teams. One part of the survey was designed to gather information on respondents’ opinions about contribution statements, as well as their impression of common practices in their fields. In a second part of the survey, we asked specifically about the paper on which the respondent was a corresponding author, and we included the paper title and publication date in the survey to facilitate respondents’ recall.

Some journals currently ask authors to use predefined categories of contributions, but different journals use different categories. A standardized approach may increase the consistency of disclosures and facilitate comparisons across journals (13, 31). It may also allow aggregation and the development of contribution-based indices to complement authorship-based indices (32). At the same time, a standardized approach would have to provide enough flexibility to accommodate heterogeneity across projects and fields.

Science already asks what share of a particular contribution was made by each co-author (ranging from 0 to 100%), although the resulting information is not publicly disclosed (Table 1). Of course, reporting this detailed information requires additional effort and may expose disagreements among co-authors, and reported contributions may not always be accurate (see table S15). Without this detail, however, evaluators are forced to infer important aspects of the value of authors’ contributions from author order, despite the considerable risk of errors.

After removing duplicate contacts, we randomly selected 17,000 of these corresponding authors for our survey. For PNAS (which publishes fewer papers than PLOS ONE), we collected contact information for papers published between January 2014 and April 2017 and randomly selected 10,000 corresponding authors for this study. Figure 3 shows the share of authors in each position who fulfill the ICMJE criteria using the weak (that is, more permissive) interpretation by team size. Table S10 shows regressions of the two variables on author position and team size. ABC Cabinets can use the contribution format for segment analysis, evaluating its two business segments and their relative contribution margins. Managers would have to determine the allocation of variable and fixed costs to each segment.

Traditional statements are required because they conform to GAAP accounting standards, and they are prepared for external audiences, including investors, lenders, and regulators. Managers at ABC Cabinets would conclude from segment analysis that the fixtures segment is more profitable because it has a higher contribution margin. Using the formulas above, they could also see that the cabinet segment needs to generate almost double the sales compared to the fixtures segment to reach the break-even point.

The total height of the bar is 381%, which means that the average first author made 3.81 different contributions. Taken together, authorship order provides some information about the underlying number and types of scientists’ contributions. However, the required inferences will often be wrong, suggesting that explicit contribution disclosures provide important additional information. Scientists universally agree that scientific articles and authorship are critically important. Ethical guidelines have been established for best practices and transparency in authorship.

For example, 94% of first authors in teams of six were involved in analyzing data, 87% in performing experiments, 86% in writing the paper, and 78% in conceiving the study. In contrast, 89% of last authors conceived the study, 85% wrote the paper, 64% analyzed data, and 23% performed experiments. Middle authors listed earlier (that is, second or third position) tend to be more involved in empirical activities what is variable cost learn why variable costs are important to a business than those listed later (that is, fourth or fifth position), but they are similarly likely to be involved in conception or writing. Regression models that use teams of all sizes and control for detailed scientific field as well as affiliation in single versus multiple laboratories (table S2) show that the differences between first, last, and middle authors are qualitatively the same as in Fig.

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