3  Guide for Authors

The current chapter should be considered an extension of the corresponding “Guide for Authors” in rOpenSci’s “Dev Guide”. The principles for package development described there also apply to statistical packages, with this chapter describing additional processes and practices for packages intended for submission to the statistical software peer review system.

The major additional process is the documentation of how a package complies with the general and category-specific standards given in Chapter 6. Statistical software packages must document compliance with the General Standards, as well as at least one set of category-specific standards. Authors need to document within the software itself every point at which it complies with every general and every applicable category-specific standard. The process of doing so is facilitated by the srr package, as described in detail in Sub-section 3.4, below.

Documenting compliance with our standards will generally entail more work than for non-statistical software submitted to our general peer review system. The first of the following sub-sections thus presents some of the benefits authors may expect from submitting their statistical software for peer-review.

The chapter then proceeds with a description of the scope of statistical software able to be considered for review, followed by descriptions of two tools intended to be used through the entire process of package development. The first tool is the pkgcheck package which should be used to confirm whether software is ready for submission or not, and enables authors to locally run the suite of checks which are automatically run on package submission. The subsequent sub-section describes our autotest tool, which is intended to be used through the entire process of package development. The third sub-section describes how use the srr package to address the major task of aligning software with our general and category-specific standards for statistical software, and the final sub-section describes the final step of specifying which grade of badge authors are aiming for.

3.1 Benefits of statistical software peer review

  • First, feedback from your reviewers and editors will increase the quality and usability of your software. Both authors and reviewers consistently report that review improves code and makes them better programmers through the feedback and interaction with each other.
  • Bringing your software into compliance with our standards will make your software easier to maintain, as many of our standards, such as those for testing and continuous integration, are designed to make sure software continues to function well as it is updated.
  • As our standards and peer-review process aim to improve the quality and completeness of documentation, going through peer-review should make your software more understandable and reduce the support you need to provide to users.
  • Approval by rOpenSci will make it easier to submit your software to repositories and journals. Packages approved by rOpenSci generally are CRAN-ready. They are eligible for expedited review at the Journal of Open Source Software, and the Journal of Statistical Software (JStatSoft) already recommends that developers refer to our standards. In our experience code peer-review is looked on favorably by reviewers of software papers at many journals.
  • In regulated environments and other fields where strong demonstration of quality and compliance is needed, approval by peer-review provides strong evidence of software quality rarely available for statistical software. Our approach to annotating within code how software meets standards makes demonstration of compliance clear and granular. We are actively working with the R Validation Hub to make approval under our system of review and standards a component of validation in regulated environments such as pharmaceutical or clinical research.

3.2 Scope

The first important task prior to submitting a package is to estimate whether a package is likely to be considered within our scope for statistical software. As described in the Overview, packages are generally considered in scope if they fit one or more of the categories listed there. Prior to submission, authors must choose one or more of these categories, and document how their software aligns with the corresponding standards given in Chapter 6, according to the procedures described below. Any software which can be aligned with one or more sets of category-specific standards will by definition be considered in scope.

Authors are encouraged to contact us at any point prior to, or during, development, to ask about whether a package might be in scope, or which categories it might fit within. Categorisation of packages may not always be straightforward, and we particularly encourage authors who are unsure about whether a package belongs in a particular category or not to contact us for discussion. An initial judgement of whether or not a package belongs in a particular category may be gained by examining the respective standards. Any package for which a large number of standards from a particular category may be considered applicable (regardless of whether or not they would actually be checked) is likely to fit within that category. Once you have determined that your package is likely to fit into one or more of our in-scope categories, you’ll need to apply our three primary development tools described in the following two sub-sections.

3.3 The pkgcheck package

The pkgcheck package can be used to confirm whether software is ready for submission or not. The checks implemented within this package are also automatically run upon submission, and packages are expected to successfully pass all checks prior to initial submission. Packages may only be submitted once the main pkgcheck() function indicates such, through clearly stating,

This package may be submitted

This function accepts a single argument of the local path to the package being checked, and returns a detailed list of checks and associated results. The return object has a summary method which prints a formatted result to the console indicating whether a package is ready for submission or not. See the main package website for more details.

The pkgcheck() function is also applied to all packages upon initial submission, in response to which our ropensci-review-bot will print the results in the issue. In the unlikely circumstances that a package is unable to pass particular checks, explanations should be given upon submission about why those checks fail, and why review may proceed in spite of such failures.

An example result of the pkgcheck() function may be seen by applying it to the skeleton srr (Software Review Roclets) package:

3.4 The autotest package

The autotest package is an automated assessment tool which all packages are expected to pass in order to be accepted for submission. The package implements a form of “mutation testing,” by examining the types of all input parameters, implementing type-specific mutations, and examining the response of each function in a package to all such mutations. This kind of mutation testing is a very effective way to uncover any unexpected behaviour which authors themselves might not necessarily pre-empt. The purpose of using autotest to prepare packages is to avoid as much as possible the common situation of reviewers discovering bugs when they attempt to use software in ways that differ from typical uses envisioned by authors themselves. Reviews of software prepared with the help of autotest should be less burdened by discussions of what are often minor technical details, and more able to focus on “higher level” aspects of software quality.

Full documentation of how to use autotest in package development is provided on the package website, and we particularly encourage any authors intending to develop packages for submission to our peer review system to step through the main autotest vignette, and to apply autotest continuously throughout package development, to ensure that autotest_package() returns clean (NULL) results when the package is first submitted.

3.5 The srr package

Once a package has been sufficiently developed to begin alignment with our standards, and once all issues revealed by autotest have been addressed, authors will need to use our third tool, the ssr (software review roclets) package to insert both general and category-specific standards into their code, and to begin the process of documenting within the code itself how and where the code adheres to the individual standards. The srr package can be installed locally by running either one of the following two lines.


srr procedures are described in detail on the package website, and in particular in the main vignette. Authors are first encouraged to obtain a local copy of the source code for that vignette, and to step through each line in order to understand how the procedure works. Having done that, you may then insert standards into your own package by running the following line from within the local directory of your package,

srr_stats_roxygen (category = c ("<category-1>", "<category-2>"))

That will insert a new file into the R/ directory of your package called (by default) srr-stats-standards.R. All standards initially have a roxygen2 tag of @srrstatsTODO, to indicate that these standards are yet to be addressed. These tags are processed by the srr roclet which needs to be connected with your package by modifying the Roxygen line of your DESCRIPTION file to the following form:

Roxygen: list (markdown = TRUE, roclets = c ("namespace", "rd", "srr::srr_stats_roclet"))

You do not need to add the srr package anywhere else in your DESCRIPTION file, nor do you need to retain this line when submitting packages to CRAN (or elsewhere). You should nevertheless retain the line at all other times, and you can easily disable the roclet output by including #' @srrVerbose FALSE somewhere within your documentation. Note that srr documentation lines are used only to produce on-screen output triggered by running roxygen2::roxygensise(), or the equivalent function, devtools::document(), and do not appear in actual package documentation.

The srr roclet recognises and process three tags:

  1. @srrstatsTODO to flag standards yet to be addressed;
  2. @srrstats to flag standards which have been addressed, and followed by descriptions of how your code addresses those standards; and
  3. @srrstatsNA to flag standards which you deem not to be applicable to your code, followed by explanations of why you deem those standards not applicable.

The file generated by srr_stats_roxygen() initially contains two roxygen2 blocks, the first containing every standard potentially applicable to your package, tagged with @srrstatsTODO, and the second with a title of NA_standards, to document standards deemed not applicable. The first task after having generated this file is to move standards to approximate locations within your package where they are likely to be addressed. For example, standards concerning tests should be moved somewhere within the tests/ directory, standards concerning documentation to the main README.Rmd file, or within a vignette file. The package skeleton includes code demonstrating how to include roclet tags within .Rmd files.

Moving different standards to more appropriate locations within your code will break down an initially large single list of standards into more manageable groups dispersed throughout your code. As each standard is addressed, it should be moved to one or more locations in your code as near as possible to relevant code, the tag changed from @srrstatsTODO to @srrstats, and a brief description appended to explain how that standard is addressed. Standards deemed not to be applicable to your package should all be grouped together within a single roxygen2 block with a title of NA_standards, each with a tag of @srrstatsNA, and a brief description of why those standards are deemed not to be applicable.

Software to be submitted for review must contain no @srrstatsTODO tags – that is, all standards must have been addressed by modifying every tag to either @srrstats or @srrstatsNA, as described above. Two useful functions to aid package alignment with standards are:

  1. The srr_stats_pre_submit() function, which confirms that all standards have been addressed prior to submission.
  2. The srr_report() function, which generates a summary report with hyperlinks to locations within your code at which all standards are placed.

The output of both of these functions are included in the result of the pkgcheck() function, both when run locally, and as run upon initial package submission. The srr_stats_pre_submit() function can be used locally to confirm that,

✔ All applicable standards have been documented in this package

while the result of the srr_report() function may be accessed through the link given in the pkgcheck output, or it can be viewed by calling that function directly.

3.6 Gold, Silver, and Bronze Badges

All statistical software which is recommended for acceptance by reviewers is entitled to display an rOpenSci badge. This badge is a modified version of the badge for the current peer-review system, with an additional section on the far right indicating the version of that standards against which the software was assessed, coloured according to the “grade” of the badge. The three possible badges look like this:

bronze for software which is sufficiently or minimally compliant with standards to pass review.

silver for software for which complies with more than a minimal set of applicable standards, and which extends beyond bronze in least one notable way, as explained below.

gold for software which complies with all standards which reviewers have deemed potentially applicable.

The submission template for statistical software submissions requires authors to identify the grade they wish to attain from the review process. These standards are not static, and it is always possible to elevate a badge to a higher grade subsequent to review. Badge grades may also be downgraded for code which is not continuously aligned with ongoing developments in standards. The following sub-sections provide further clarification of each grade.

3.6.1 Bronze

Software which is sufficiently or minimally compliant with standards will receive a bronze badge. One common reason for this badge is software which authors do not intend to develop further following review. This commonly arises for software produced from research projects which have been completed, leaving no funding to further develop the software. Another reason might be that software has been developed for a particular use case, with authors unable to align it with additional standards in order to expand its general utility. A bronze badge need not signify any weakness or inadequacy in software, rather it will generally signify software which has been developed for one particular use case, and which will not be subject to significant further development.

3.6.2 Silver

Silver badges are granted to software which extends beyond the minimal requirements of bronze in at least one the following four aspects:

  • Compliance with a good number of standards beyond those identified as minimally necessary. This will require reviewers and authors to agree on identification of both a minimal subset of necessary standards, and a full set of potentially applicable standards. This aspect may be considered fulfilled if at least one quarter of the additional potentially applicable standards have been met, and should definitely be considered fulfilled if more than one half have been met.
  • Demonstrating excellence in compliance with multiple standards from at least two broad sub-categories. Sub-categories are distinguished in the Standards Chapter by three numbers, so that the General Standards have five sub-categories numbered 6.1.1 to 6.1.5. This aspect would require software to extend notably beyond the requirements of two or more standards in at least two sub-categories (regardless of whether general or category-specific standards). For example, software which might otherwise be assessed at bronze grade, yet which is both excellently documented, and has an outstanding test suite, may be considered to fulfil this aspect.
  • Have a demonstrated generality of usage beyond one single envisioned use case. Software is frequently developed for one particular use case envisioned by the authors themselves. Generalising the utility of software so that it is readily applicable to other use cases, and satisfactorily documenting such generality of usage, represents another aspect which may be considered sufficient for software to attain a silver grade.
  • Internal aspects of package structure and design. Many aspects of the internal structure and design of software are too variable to be effectively addressed by standards. Packages which are judged by reviewers to reflect notably excellent design choices, especially in the implementation of core statistical algorithms, may also be considered worthy of a silver grade.

3.6.3 Gold

To attain a gold badge, software must comply with all applicable standards, and must also fulfil at least three of the four aspects described above for silver-grade badges. Both the applicability of standards, and fulfilment of these three aspects, will ultimately determined by reviewers. Moreover, compliance with all grades is assessed against current standards, meaning that a gold badge must be actively maintained as standards themselves are revised and updated.