Sam Tyner

The free online book [*Open Forensic Science in
R*](https://sctyner.github.io/OpenForSciR/) was created to foster open
science practices in the forensic science community. It is comprised of
eight chapters: an introduction and seven chapters covering different
areas of forensic science: the validation of DNA interpretation systems,
firearms analysis of bullets and casings, latent fingerprints, shoe
outsole impressions, trace glass evidence, and decision-making in
forensic identification tasks. The chapters of *Open Forensic Science in
R* have the same five sections: Introduction, Data, R Package(s),
Drawing Conclusions, and Case Study. There is R code throughout the
chapter to guide the reader along in an analysis, and the case study
walks the reader through solving a forensic science problem in R, from
reading the data to answering a specific question such as, "Were these
two bullets fired by the same gun?"

### The Center for Statistics and Applications in Forensic Evidence (CSAFE)

To help more scholars access forensic science research, *Open Forensic
Science in R* brings together many open resources created and/or used by
the Center for Statistics and Applications in Forensic Evidence
([CSAFE](https://forensicstats.org/)) and the National Institute for
Standards and Technology ([NIST](https://www.nist.gov/)). CSAFE was
founded in 2015 with the mission of building up the statistical
foundations in forensic science. CSAFE is an interdisciplinary NIST
[Center of Excellence](https://www.nist.gov/coe) comprised of four
institutions: Iowa State University (ISU), Carnegie Mellon University
(CMU), University of California Irvine (UCI), and University of Virginia
(UVA). The statistics faculty members, postdoctoral researchers, and
graduate students working with CSAFE have written many R packages to
complete a variety of forensic science tasks, from analyzing shoeprint
impressions to comparing marking on bullets. *Open Forensic Science in
R* brings many of these forensic science R packages together in one
place.

CSAFE is
[committed](https://forensicstats.org/blog/2017/11/29/open-source-software-applications-forensics-courtroom/)
to open science, and many CSAFE researchers contributed to *Open
Forensic Science in R*. As most CSAFE researchers are statisticians,
much of CSAFE's research uses R in some capacity. Dedication to open
source is vital for advancing the field of forensic science because the
current barrier to entry into forensic science research is very high:
equipment is very expensive and most software in the field is
proprietary, so no one outside of the company selling the software knows
exactly how it works. These barriers limit the number of researchers who
have access to the field. There are also limited data available to
researchers. In many cases, data are limited for practical reasons
because they are from real, identifiable people and investigations.
CSAFE is committed to releasing as much data as possible to help advance
forensic science research, and hosts a large [Forensic Science Data
Portal](https://forensicstats.org/data/) to make the data widely
available. *Open Forensic Science in R* brings many of the open
resources available to current and future forensic science researchers
together in one place to encourage openness in the field.

### Example: Comparing Bullets

::: {.gallery .caption-position-bottom .caption-effect-slide .hover-effect-zoom .hover-transition itemscope="" itemtype="http://schema.org/ImageGallery"}
::: {.box}
<figure itemprop="associatedMedia" itemscope=""
itemtype="http://schema.org/ImageObject">
<div class="img"
style="background-image: url(&#39;/img/blog-images/2019-08-20-forensic-science/bullet1.png&#39;);">
<img src="/img/blog-images/2019-08-20-forensic-science/bullet1.png"
itemprop="thumbnail" alt="bullet 1" />
</div>
<a href="/img/blog-images/2019-08-20-forensic-science/bullet1.png"
itemprop="contentUrl"></a>
<figcaption><p>bullet 1</p></figcaption>
</figure>
:::

::: {.box}
<figure itemprop="associatedMedia" itemscope=""
itemtype="http://schema.org/ImageObject">
<div class="img"
style="background-image: url(&#39;/img/blog-images/2019-08-20-forensic-science/bullet2.png&#39;);">
<img src="/img/blog-images/2019-08-20-forensic-science/bullet2.png"
itemprop="thumbnail" alt="bullet 2" />
</div>
<a href="/img/blog-images/2019-08-20-forensic-science/bullet2.png"
itemprop="contentUrl"></a>
<figcaption><p>bullet 2</p></figcaption>
</figure>
:::
:::

The chapter ["Firearms:
bullets"](https://sctyner.github.io/OpenForSciR/bullets.html) begins by
introducing the reader to the terminology of firearms and bullets, and
describes the methods used in forensic science to compare bullets. Then,
the chapter discusses the open source work by current and former CSAFE
researchers. Three dimensional bullet scans, the data of interest, are
stored in the [x3p](https://sourceforge.net/p/open-gps/mwiki/X3p/)
standard format, and the R package
[`x3ptools`](https://heike.github.io/x3ptools/) is used to read the
bullet scans in R ^[1](#fn:1){.footnote-ref role="doc-noteref"}^. Then,
the bullet data are analyzed with the
[`bulletxtrctr`](https://heike.github.io/bulletxtrctr/) package
^[2](#fn:2){.footnote-ref role="doc-noteref"}^. Each bullet is comprised
of many surface scans corresponding to the number of
[lands](https://sctyner.github.io/OpenForSciR/glossary.html#def:gunbarrel)
on the bullet which came in contact with the gun barrel when fired. The
number of surface scans varies by type and manufacturer of the gun. For
a comparison of two bullets, a representative cross-section of each 3D
surface scan is selected, the curve is removed, some noise is removed,
and only the smoothed *bullet signature* remains. (See Figure 2.) This
procedure is repeated for all lands of the bullets of interest, and the
signatures are compared to each other using a trained random forest
available in the package, resulting in scores from zero to one
indicating how similar the two signatures are ^[3](#fn:3){.footnote-ref
role="doc-noteref"}^. In this case, bullets 1 and 2 were fired from the
same gun, which can be seen by comparing the bullet 1 lands 2, 3, 4, 5,
6, 1 to the bullet 2 lands 3, 4, 5, 6, 1, 2, respectively. For complete
details, see the [Case
Study](https://sctyner.github.io/OpenForSciR/bullets.html#case-study-1)
section of the chapter.

::: {.gallery .caption-position-bottom .caption-effect-slide .hover-effect-zoom .hover-transition itemscope="" itemtype="http://schema.org/ImageGallery"}
::: {.box style="max-width:50%"}
<figure itemprop="associatedMedia" itemscope=""
itemtype="http://schema.org/ImageObject">
<div class="img"
style="background-image: url(&#39;https://sctyner.github.io/OpenForSciR/open-forensic-science-in-r_files/figure-html/bullets-cscrosscut-1.png&#39;);">
<img
src="https://sctyner.github.io/OpenForSciR/open-forensic-science-in-r_files/figure-html/bullets-cscrosscut-1.png"
itemprop="thumbnail" />
</div>
<a
href="https://sctyner.github.io/OpenForSciR/open-forensic-science-in-r_files/figure-html/bullets-cscrosscut-1.png"
itemprop="contentUrl"></a>
</figure>
:::

::: {.box style="max-width:50%"}
<figure itemprop="associatedMedia" itemscope=""
itemtype="http://schema.org/ImageObject">
<div class="img"
style="background-image: url(&#39;https://sctyner.github.io/OpenForSciR/open-forensic-science-in-r_files/figure-html/bullets-cssigs-1.png&#39;);">
<img
src="https://sctyner.github.io/OpenForSciR/open-forensic-science-in-r_files/figure-html/bullets-cssigs-1.png"
itemprop="thumbnail" />
</div>
<a
href="https://sctyner.github.io/OpenForSciR/open-forensic-science-in-r_files/figure-html/bullets-cssigs-1.png"
itemprop="contentUrl"></a>
</figure>
:::
:::

### How to Contribute & Acknowledgements

The book will continue to grow, and contributions are welcome via issues
or pull requests on the [Github
repo](https://github.com/sctyner/OpenForSciR). If you would like to
contribute, please follow our [Contributor Code of
Conduct](https://github.com/sctyner/OpenForSciR/blob/master/CODE_OF_CONDUCT.md).
Thank you to the many CSAFE and NIST researchers who contributed to this
project: [Dr. Heike Hofmann](https://hofmann.public.iastate.edu/) (ISU),
Dr. Soyoung Park (ISU), [Xiao Hui Tai](http://www.stat.cmu.edu/~xtai/)
(CMU), [Dr. Eric Hare](https://twitter.com/ericrhare) (Omni Analytics,
formerly ISU), [Dr. Karen
Kafadar](https://statistics.as.virginia.edu/faculty-staff/profile/kk3ab)
(UVA), Karen Pan (UVA), [Dr. Amanda
Luby](https://twitter.com/amandaluby) (CMU), and Dr. Sarah Riman (NIST).
Finally, a big thank you goes to the [rOpenSci Fellowship
program](/blog/2018/02/14/announcing-2018-ropensci-fellows/) for funding
this project.

::: {.footnotes role="doc-endnotes"}

------------------------------------------------------------------------

1.  ::: {#fn:1}
    Heike Hofmann, Susan Vanderplas, Ganesh Krishnan and Eric Hare
    (2019). x3ptools: Tools for Working with 3D Surface Measurements. R
    package version 0.0.2.9000.
    <https://github.com/heike/x3ptools> [↩︎](#fnref:1){.footnote-backref
    role="doc-backlink"}
    :::

2.  ::: {#fn:2}
    Heike Hofmann, Susan Vanderplas and Ganesh Krishnan (2018).
    bulletxtrctr: Automatic Matching of Bullet Striae. R package version
    0.2.0.
    <https://heike.github.io/bulletxtrctr/> [↩︎](#fnref:2){.footnote-backref
    role="doc-backlink"}
    :::

3.  ::: {#fn:3}
    Hare, Eric, Heike Hofmann, and Alicia Carriquiry. 2017. "Automatic
    Matching of Bullet Land Impressions." *The Annals of Applied
    Statistics* 11 (4): 2332--56. [↩︎](#fnref:3){.footnote-backref
    role="doc-backlink"}
    :::
:::


The free online book
<em>
 Open Forensic Science in R
</em>
was created to foster open science practices in the forensic science community.

Messaggi di Rogue Scholar

Introducing Open Forensic Science in R