CodingWithOmop

Please note the below instructions are rather vague. There are certainly non-obvious steps missing below so please ask as you go.

Analyst track

A.1. Preparing CohortDiagnostics

The aim here is to prepare the code to run cohort diagnostics for a set of study-specific cohort definitions. If you don't currently have a project that needs phenotypes, you could choose definitions related to: 1) dementia, 2) COVID-19, 3) mental health disorders (as we have ongoing projects related to each). Please keep in mind the purpose of this exercise is not necessarily to get final study cohort definitions in a couple of days, but rather to give you experience on setting up and interpreting the results from cohort diagnostics.

Steps:

1. Develop the required concept sets, either by running CodelistGenerator (https://github.com/oxford-pharmacoepi/CodelistGenerator, https://oxford-pharmacoepi.github.io/CodelistGenerator/) or by taking a concept set from a previous study (https://github.com/oxford-pharmacoepi/OmopConceptSetLibrary). Note, there are other options to go about this but by using these two new tools, you can help find bugs or areas where documentation is lacking (in which case please open an issue on the respective github repos).
2. Build cohort definitions using the concept sets, adding the required cohort logic (e.g. taking first event in history, with no eligibility criteria other than the initial event, and cohort end date being end of observation period - but this could differ depending on the study in question).
3. Take the code from this Dementia CohortDiagnostics (https://github.com/oxford-pharmacoepi/DementiaDusCohortDiagnostics - download rather than fork), and switch out the existing cohort definitions to your ones.
4. Upload to this github repo by creating a branch (with the option and your name as the name, e.g. "A1_EdBurn") and open a pull request. I would suggest that you use github desktop to help with this.
5. Persuade someone to do a code review and accept your pull request (after discussing any queries and fixing any bugs).
6. Persuade someone to run the cohort diagnostics and return the results
7. Review the results - would you make any changes to your definition based on your results?

A.2. Write custom code to characterise a cohort

The aim here is to prepare some code in an R project to further characterise patients in a cohort in a results table in the omop cdm (taking them to be in the standard cohort table format - whether creator by CohortGenerator or otherwise). For example, this code could be to produce a table 1 based on characteristics relative to cohort start date (e.g. age, sex, prior observation time, etc), or it could be a figure like a histogram (e.g. age at cohort entry, time between cohort start and end date, etc).

Steps:

1. Develop the code yourself (if you don't have access to a live database, you could do this with Eunomia https://github.com/OHDSI/Eunomia)
2. Upload the code to this github in the same way as in step 4) in A.1. above
3. Persuade someone to do a code review and accept your pull request.
4. Persuade someone to run the code and return results (make sure there is no results with counts of less than 5)
5. Review the results - would you make any changes to your code based on the results?

Developer track

D.1. Contributing to CodelistGenerator

The aim here is to act as a contributor to the Codelistgenerator package (https://oxford-pharmacoepi.github.io/CodelistGenerator/). This does not necessarily involve any programming, as for example queries relating to the documentation would be very helpful.

Steps:

1. Read through the package vignettes (https://oxford-pharmacoepi.github.io/CodelistGenerator/articles/Introduction_to_CodelistGenerator.html and https://oxford-pharmacoepi.github.io/CodelistGenerator/articles/Options_for_CodelistGenerator.html)
2. Install the package and run an example
3. Perform code review. Fork the package, and work through through the main functions locally.
4. Can you add any tests? Add to branch and open a pull request for review (probably by Ed).
5. Could you add to the existing vignettes or add a new one (e.g. examples for medications and procedures would be nice to have). If so discuss with Ed and add to the code (note, there is some precomputation for vignettes that is a little confusing - ask Ed about it if you are writing a new one).
6. Do you have any queries about whether something is unclear, might be a bug, or do you see possibilities for improvement to existing functions or possible extensions? Open an issue to discuss. After discussion, you could work on the code and open a pull request for review.

D.2. Build a package

This could take a lot of different forms, but my sugestion would be - creating themes for common types of plots. See bbplot https://github.com/bbc/bbplot, https://github.com/hrbrmstr/hrbrthemes, https://github.com/AtherEnergy/ggTimeSeries, https://github.com/delabj/ggCyberPunk for some inspiration. The idea would be to have functions like "+ gg_pde_time_series()" which formats a time series plot, "+ gg_pde_ps()" which formats a propensity score distribution plot, etc. See D2_ExamplePlots/basic_plots.R for some example plots which can be much improved.

Steps:

1. Work on creating a function locally first (before worrying about how to put the package together). Probably this approach is the easiest to replicate https://github.com/bbc/bbplot/blob/master/R/bbc_style.R to start with.
2. Now once you have a function, put it into a package with only that function using devtools::create_package(). See https://r-pkgs.org/index.html for many more instructions on what this can involve (for example, usethis::use_r("name_of_function") will create the R file where you will put that function). But for now, continue to work on it locally (but now as a package).
3. Once you can run for an example or two, push to github and persuade someone to do an initial code review. Are they able to install the package and run your example? Can they use for another example. Iterate based on their feedback.
4. Before adding more functions start addding tests for the existing one (run usethis::use_test("name_of_function") to set up). Use covr to check test coverage. Can you get it to 100%?
5. Consider how many dependencies your package has, can any be avoided?
6. Now you can start adding more functions etc!