Jon Calder

Posts

Mon, 04 Dec 2017 00:00:00 +0000

Mon, 01 Jan 0001 00:00:00 +0000

Privacy Policy for Arboreal

Last updated: 5 May 2026

This Privacy Policy describes how Arboreal (“the App”, “we”, “us”) handles information when you use the mobile application. By using the App you agree to the practices described below.

1. Information we collect

We do not ask you for personal information. The App has no accounts, no sign-in, and no user profiles.

The App does collect or process the following limited information:

a. Locally-stored game progress

Your level completion and star ratings are stored on your device only, using your device’s local storage. This data never leaves your device, is not transmitted to us, and is removed when you uninstall the App.

b. Information collected by third-party services

The App uses a small number of third-party SDKs that may collect information automatically. We do not receive personal information from these services; they operate under their own privacy policies, linked below.

Google AdMob — serves interstitial advertisements to users on the free tier. AdMob may collect device identifiers, IP address, and ad-interaction data to deliver and measure ads. Premium (“Arboreal Pro”) users are not shown ads, but the SDK may still be initialised. Privacy policy: https://policies.google.com/privacy
RevenueCat — processes in-app purchases (the one-time “Arboreal Pro” unlock) and tracks entitlement status. RevenueCat receives an anonymous app-user ID, purchase receipts, and basic device/platform metadata. Privacy policy: https://www.revenuecat.com/privacy
Google Play Billing — processes the actual purchase transaction. We never see your payment details. Privacy policy: https://policies.google.com/privacy
Expo / React Native runtime — standard mobile app runtime; does not collect personal information by itself in this App.

We do not use analytics, crash reporting, push notifications, location services, the camera, the microphone, your contacts, or your photos.

2. How we use information

The limited information processed by the App is used solely to:

Save your game progress locally on your device.
Show advertisements (free tier only).
Verify your “Arboreal Pro” purchase and unlock the corresponding levels and ad-free experience.

We do not sell, rent, or share information with third parties for marketing.

3. Children’s privacy

Arboreal is suitable for general audiences and is not directed specifically at children under the age of 13. We do not knowingly collect personal information from children. If you believe a child has provided personal information through one of the third-party services listed above, please contact us and we will work with the relevant provider to address it.

4. Advertising and personalised ads

Free-tier users see interstitial ads served by Google AdMob. Depending on your device settings and region, these ads may be personalised based on identifiers managed by your operating system. You can limit ad personalisation at any time:

Android: Settings → Google → Ads → “Delete advertising ID” or “Opt out of Ads Personalization”.

Purchasing “Arboreal Pro” removes all advertisements from the App.

5. In-app purchases

The App offers a single one-time purchase, “Arboreal Pro”, which unlocks additional levels and removes advertisements. Purchases are processed by Google Play Billing and managed by RevenueCat. Refunds are handled through Google Play according to its standard refund policy.

6. Data retention and deletion

Local progress data persists on your device until you uninstall the App or clear its storage.
Data held by Google AdMob, RevenueCat, and Google Play Billing is retained according to their respective policies.
To request deletion of any data held by those third-party services, please consult their privacy policies linked above.

7. Security

We rely on the security mechanisms provided by your device’s operating system and by the third-party services listed above. No method of electronic storage or transmission is 100% secure.

8. Changes to this policy

We may update this Privacy Policy from time to time. The “Last updated” date at the top will reflect any changes. Continued use of the App after an update constitutes acceptance of the revised policy.

9. Contact

If you have any questions about this Privacy Policy, please contact me via the contact form

About Me

Mon, 01 Jan 0001 00:00:00 +0000

Hi, I’m Jon.

I’m a data scientist, R enthusiast, hobbyist musician, hopeful runner and lifelong learner. I work as an automation engineer at Libryo, where I am engaged in the use of computation to assist with content ingestion, analysis, and anything else it might be able to help us with. I live in the beautiful city of Cape Town and I am proudly South African.

Please feel free to connect with me! Either send me a direct message using the form available on the Contact page, or have a look at the footer for my social media, Github and other links.

For a more lengthy bio, keep on reading below!

Bio

I grew up in the heart of Kwa-Zulu Natal, South Africa, in a small city called Pietermaritzburg - aka ‘the sleepy hollow’. Located about 90km away from the heart of Durban, PMB is probably best known for being the (joint) home of the world’s largest and oldest ultramarathon - the Comrades Marathon - which is run between these two cities.

My dad and I after Cape Town 12 (2016)

Running is probably the simplest sport there is, but certainly not the easiest, and a race of this distance presents a substantial challenge - both physically and mentally. I grew up watching the race on tv, out alongside the road and sometimes even looking over the wall from the garden (when the race went past our house). To this day, I remain in awe of the thousands of people who complete this journey each year. One of those people is my father, who has 13 Comrades medals to his name. I remember him once saying of the race, “you will learn things about yourself you wouldn’t discover another way”. I think I’d like to complete the Comrades Marathon one day.

But don’t let that give you the wrong impression - most of the stuff that I’m drawn to generally falls much more towards the mental end of the physically vs mentally demanding spectrum…

I’ve always been something of an academic. I thrived in the structured learning environment that school, and later university provided me. Learning is something that I really enjoy and I hope to be someone who never stops learning, both intellectually and otherwise.

I left PMB in 2005 to study at the University of Cape Town - tackling three years of actuarial science before switching streams to graduate with a BSc in Mathematical Statistics. During my honours the following year I discovered the world of Operations Research and Decision Science in particular which really piqued my interest. So after completing my BSc Honours in Statistics, I ended up undertaking an MSc in Operations Research, sparked by stakeholders from the Stormers rugby franchise in the Western Cape.

This resulted in a research project which combined aspects of sports science, decision theory, and a whole lot of modelling and simulation in R. Although I was first introduced to R at the outset of my undergraduate years at UCT, it was here where I began to develop my enthusiasm for R as a programming language.

During the latter part of my MSc, in 2011, I started working in the software industry as a data analyst for RightShift - a tech startup developing online games. The company experienced rapid growth in it’s player base, which gave me good exposure to some of the challenges of managing and manipulating large amounts of data. Our core tooling included MySQL, SQL Server, and much of the Microsoft Business Intelligence stack - SSAS, SSIS and SSRS - along with a good deal of Excel. Over and above that I also did a few projects which leveraged R to embed dynamic reports and visualizations on the company wiki, and for some Shiny apps.

I completed my MSc in 2013, and produced two publications (see here) shortly thereafter with the help of my supervisor Dr Ian Durbach. RightShift was acquired by Derivco in 2015/2016, which saw me transition into more of a product design role, but with a particular focus on modeling all math related aspects of game design. Then in 2017, I joined one of the data science teams at Derivco, which allowed me to be more involved facilitating product analysis on an ongoing basis.

At the beginning of 2018 I joined Libryo - a legal-tech start-up founded in London by three South African entrepeneurs. Libryo is an organisation on a mission to make it easier for companies to know the law, and keep it. We’re on an exciting journey, and my part in it is only just beginning!

In my spare time, I enjoy running, a myriad of different forms of moving images (sport, e-sport, movies, tv series etc), listening to music, and - when we can find time - making music with my brother and other friends (for more info see ryancalder.co.za). I am also a keen sound engineer with a casual interest in various aspects of both studio and live production. Along with all of this I am also trying to be more involved in R and other open-source development, and hope to continue growing my technical skillset in pursuit of becoming a more rounded data scientist.

Contact Me

Mon, 01 Jan 0001 00:00:00 +0000

Curriculum Vitae

Mon, 01 Jan 0001 00:00:00 +0000

Jon Calder

“No man should escape our universities without knowing how little he knows.” – J. Robert Oppenheimer

Experience

February 2018 - Present

Automation Engineer; Libryo

Research and development on how to best automate & augment processes on the Libryo Platform
Database management, maintenance and support
Data analysis, dashboarding and reporting
Software development and maintenance of development, staging and production environments
Strategic support and consultation around technology decisions
Assist with the management and implementation of strategic objectives

September 2017 - Present

Guest Lecturer; University of Cape Town

Data Science for Industry is a 24-lecture, 12 credit module in the MSc in Data Science program at the University of Cape Town
Teaching material for the development of (1) R packages and (2) Shiny apps which comprise the communication section of the course

September 2016 - January 2018

Data Scientist; Derivco - Cape Town

work with product and design teams to inform and assist with product and feature design
assist with both functional and technical product documentation
conduct ongoing industry and competitor research to inform the design of product features
determine product data requirements and support delivery of data, monitoring and analysis to operators
expand on underling game maths and service maths requirements for product features as they are designed, developed & iterated upon
develop tools to model and simulate the impact of changes to product configuration

October 2011 - August 2016

Data Analyst; RightShift

design, build and maintain ETL process to update database environments as well as deploy and manage SSAS cubes, and optimizing these processes in order to allow for rapid scaling}
create, manage and maintain reports to service the daily, weekly and monthly requirements of the business in various respects; as well as reporting directly to high level management
measure application data in order to identify trends in player behaviour, virality, revenue and associated key metrics
track and monitor general application performance across multiple platforms and identify potential bugs and problems
assist marketing and customer support teams with additional tailored reporting and analysis to provide specific insight into various interventions and offers
perform ongoing analysis in order to inform decision making on game and meta-game development and configuration utilizing A-B testing

2008 - 2011

Student Tutor; University of Cape Town, Department of Statistics

Tutored undergraduate statistics courses from 1st year through to 3rd year
Responsibilities involved:
- facilitating weekly class tutorials
- invigilating & marking of tests and exams
- ad-hoc one-on-one hot-seat tutoring

2008 - 2011

Senior Tutor; Axiom Tutoring

Tutoring of mathematics and statistics from high school through to undergraduate university level
e-mail administration & allocation of tutors to students
one-on-one & small group tutoring
preparation & typesetting of notes and worksheets

2007 Summer

Student Internship; Momentum Collective Benefits

worked as part of a group recording, capturing and compiling historical data for later use by the actuarial team to re-evaluate exposure to risk
gained insight into the insurance/group life industry, and experience in the commercial use of Microsoft Excel and VBA macros to automate data compilation and processing tasks

Publications

Modelling uncertainty in stochastic multicriteria acceptability analysis

Ian N. Durbach, Jon M. Calder
Omega (October 2015)
Available at: http://dx.doi.org/10.1016/j.omega.2015.10.015

Decision Support for Evaluating Player Performance in Rugby Union

Jon M Calder, Ian N. Durbach
International Journal of Sports Science & Coaching (February 2015)
Available at: http://dx.doi.org/10.1260/1747-9541.10.1.21

Technical Experience

Software & Programming Languages

R, C++, Java & Python

Proficient with R, some experience with C++, Java, Scala & Python

Databases & Scripting

MySQL, T-SQL, Excel, VBA, SSAS, SSMS, SSRS + limited experience with MDX

Document Preparation

Word, Powerpoint, Markdown, LaTeX

Statistical Packages

Some experience with Statistica, SPSS, EViews & Genstat

Web Development

Some experience with HTML & CSS, PHP, Javascript, Wordpress

Education

2009 - 2013

MSc in Operations Research (with distinction); University of Cape Town, Department of Statistics

Decision modeling, decision support, logical fallacies & reasoning, performance analysis in sport.

Player performance evaluation in rugby using Stochastic Multi-Criteria Acceptability Analysis with simplified uncertainty formats

Masters dissertation

Supervisor: Dr Ian Durbach

Description: This study investigates the use of SMAA as a decision support tool for rugby coaches by making use of game data to inform possible rankings of players within positional profiles based on preference criteria.

2008

BSc (Honours) in Statistics; University of Cape Town, Department of Statistics

Operations Research, Decision Modelling, Theory of Statistics, Multivariate Analysis, Econometrics, Portfolio Management.

Application of Rasch Analysis to the Assessment of Grade 6 Literacy and Numeracy In The Western Cape

Honours dissertation

Supervisors: Prof Tim Dunne, Kutlwano Ramaboa

Description: Rasch analysis is utilized to assess the validity of a numeracy and literacy test administered to grade six learners from over 1000 schools in the Western Cape in 2007. Rasch analysis is introduced in the context of a background to modern test theory, and the data are then examined with respect to invariance across the latent trait, targeting and reliability, item characteristics and differential item function.

2005 - 2007

BSc in Statistics; University of Cape Town, Department of Statistics

Undergraduate courses included Statistics, Mathematics, Computer Science, Economics, Accounting, Finance and Actuarial Science

2000 - 2004

Carter High School; Pietermaritzburg, South Africa

Finished fourth in the Vulindlela/Pietermaritzburg district and third in the Midlands Area (awarded by the Kwa-Zulu Natal Department of Education)
Awarded the dux prize for top scholar in Grade 12, with distinctions for English, Afrikaans, Mathematics, Biology, Physical Science and Geography
Awarded Academic Colours in Grade 10 and Academic Honours in Grades 11 and 12.
Awarded Effort Certificates from Grade 8-12

Human Languages

English (home language)
Afrikaans (2nd language)
French (beginner)

Achievements and Extra Murals

Music

Studied classical piano - theory and practical - at the Music School in Pietermaritzburg (1998-2003)
Was graded at various Eistedfords during this period and performed at additional concerts
Achieved a grade 6 performance level

Sport

1st Team Outdoor hockey (Captain) and 1st Team Indoor hockey at Carter High School
Awarded half colours
Other sports played (mostly club/social) while at school and university include: soccer (indoor and outdoor), action cricket, cricket, squash, touch rugby and ultimate frisbee

Community Service

Since 2017: Member of RWeekly
Since 2017: Co-organiser of satRdays in South Africa (e.g. see satRday CT 2018)
Since 2017: Mentor and maintainer of the R track on exercism.io
2007: 1st Year mentor, Smuts Hall (UCT Residence)
2004: Grade 8 mentor, Carter High School
2003: Member of Matric Dance Committee, Carter High School

Interests & Hobbies

Piano/Keyboard
Sound engineering
Running

Projects

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Open Source Projects

rweekly.org

Weekly Updates from the Entire R Community

I am an active contributor and part of the core team

exercism.io

Download and solve practice problems in over 30 different languages

I am currently a maintainer of the R track

R packages I’ve collaborated on

styler: Non-invasive pretty printing of R code
pRojects: A tool for setting up R projects and related infrastructure
refactor: Better factor handling for R
exercism: An R package for interacting with the exercism.io API
precommit: pre-commit hooks for R projects
strcode: Structure your code better
gitsum: Summarise the history of any git repository

Other personal projects

exercism track config: Shiny app for visualizing track config on exercism.io
regular expressions: Swirl course on regular expressions in R
diagrammer: Swirl course for the DiagrammeR package
hugobot: A chat bot built on the Hubot framework