Table 1.
List of potential authorship contributions provided in our author survey.
If a co-author provided a service not captured in our nine listed categories, we instructed the survey participant to select “Other” and provide a brief written description of the contribution. Descriptions with superscripts represent contributions that match the Ecological Society of America (ESA)1 and International Committee of Medical Journal Editors (ICMJE)2 guidelines.
Table 2.
List of “Other” contributions provided by co-authors in surveyed studies.
Fig 1.
Box and whisker plots of the number of co-authors in manuscripts among survey participants, non-participants, and the total pool of selected studies.
Black bars represent median values, blue boxes include the interquartile range (IQR), and “whiskers” reflect 1.5 IQR. Outlier values outside of this range are represented as individual points.
Fig 2.
The cumulative diversity of individual author contributions among survey participants (n = 449).
We generated estimates by randomly sampling increasing sample sizes of survey participants and calculating the total number of unique author contributions for each sample size. Shaded area reflects the 95% confidence intervals based on 1,000 repeated samples for each sample size. The solid blue line represents interpolated estimates, the solid blue circle is the observed diversity of contributions, and the dashed line is extrapolated estimates for sample sizes greater than our actual sample size.
Table 3.
Occupations of lead authors participating in our survey at the time that their manuscripts were submitted for review and associated study compliance rates with authorship guidelines.
Percentages in a given column with different letter superscripts are significantly different (P<0.05) based on Fisher’s exact tests with Holm corrections for multiple comparisons.
Fig 3.
Hierarchical cluster analysis of author contributions for a) lead, b) middle, and c) last authors in surveyed studies with > two co-authors. Red values are approximately unbiased (AU) p-values, and blue values are bootstrap probability (BP) values (%). Clusters with AU values > 95% are enclosed in red boxes.
Table 4.
Percentage of co-authors that performed each survey contribution.
To allow for direct comparison among author positions, calculations were made for the sub-set of studies with > two co-authors for lead, middle, and last authors (n = 341). For lead and last authors, contribution percentages are also reported in parentheses for the complete dataset (n = 449 studies).
Table 5.
Summary of author contributions for 449 manuscripts published in ecological journals in 2010.
Table 6.
Summary of author contributions for 341 manuscripts published in ecological journals in 2010 with > two co-authors.
The “All Authors” column shows the percentage of all authors represented in our survey with a given contribution category. The remaining three columns show the percentage of authors of a given position (lead, middle, or last) within the same contribution category. For middle authors, we report both pooled averages as well as mean ± SD in parentheses.
Fig 4.
Plots showing the probability of study non-compliance with a) Ecological Society of America (ESA) and b) International Committee of Medical Journal Editors (ICMJE) guidelines in relation to the number of co-authors per study. For ESA guidelines, probability of non-compliance also varied in relation to lead author occupation. Separate curves reflect non-compliance probability for studies led by graduate students (dashed light blue), post doctoral researchers (solid red), other professions (solid dark blue), research scientists (dotted red), and professors (dotted light blue). Our survey did not explicitly ask about the last ICMJE requirement, approval of the final submitted version of the manuscript, so our classification of ICMJE compliance does not consider this third criterion.
Table 7.
Results of logistic regression analyses of the probability of Ecological Society of America (ESA) and International Committee of Medical Journal Editors (ICMJE)1 non-compliance in relation to the number of co-authors and lead author professional position.
All author position data are scaled relative to professor lead authors.
Table 8.
Model Akaike information criterion with correction for small sample sizes (AICc) comparisons of probability of authorship non-compliance with the Ecological Society of America (ESA) and International Committee of Medical Journal Editors (ICMJE)1 authorship guidelines.
Values are ΔAICc (AICc Model—AICc Minimum). The best model for each dataset has the lowest AICc value (i.e., ΔAICc = 0).