Developer Guide: sprtt Package

Overview

The sprtt package follows a modular architecture with clear separation of concerns:

1. Main User-facing functions (seq_ttest(), seq_anova()) handle input validation and provide clean interfaces

2. Utility User-facing functions provide supporting functionality (plotting, data generation, caching)

3. Builder functions (build_seq_*_arguments()) Transform and validate user inputs into a structured S4 argument object. Builder functions act as a processing pipeline between the user-facing interface and the core calculation functions. They handle the complex task of parsing different input formats, validating all parameters, and packaging everything into a type-safe container.

4. Calculation functions (calc_seq_*()) perform the core computations

5. Internal utility functions (e.g., delete_na(), extract_formula(), get_seq_decision(), …) are small, focused helpers that handle specific tasks across the package. They follow the Single Responsibility Principle - each function does one thing well. This design reduces code duplication, improves testability, and makes the codebase easier to maintain.

6. Result Classes - S4 classes that store results in type-safe, structured containers. These classes provide controlled access to result components through standardized methods (@, [], and show()), ensuring consistency and extensibility.

This separation allows for:

• Easy testing of individual components
• Clear error handling at appropriate levels
• Extensibility for future sequential tests
• Consistent user experience across functions

Function Naming Convention:

• seq_*(): User-facing main functions
• build_*(): Argument preparation functions
  
• calc_*(): Computational core functions
• *_class.R: S4 class definitions

Function Structure

Table: Structure of the main seq_ttest() function (Level 1)

Level 2	Level 3	Level 4
build_seq_ttest_arguments() Class: seq_ttest_arguments	check_formula()
	extract_formula()
	get_one_sample()
	delete_na()
	check_data()	check_constant_data()
calc_seq_ttest() Class: seq_ttest_results	calc_seq_ttest_t_statistic()
	calc_seq_ttest_non_centrality_parameter()
	calc_seq_ttest_likelihoods()
	calc_seq_ttest_boundaries()
	get_seq_ttest_decision()
	build_seq_ttest_results()

Table: Structure of the main seq_anova() function (Level 1)

Level 2	Level 3
build_seq_anova_arguments() Class: seq_anova_arguments	check_formula_anova()
	extract_formula_anova()
	check_data_anova()
calc_seq_anova() Class: seq_anova_results	calc_non_centrality_parameter_anova()
	calc_group_means()
	calc_ss_effect()
	calc_ss_residual()
	calc_ss_total()
	calc_F_statistic_()
	calc_likelihoods_anova()
	calc_boundaries()
	get_seq_decision()
	calc_effect_sizes()
	build_seq_anova_results()
calc_plot_anova() Class: seq_anova_results

Continuous Integration

Pre-release

• Update version number in DESCRIPTION
• Update NEWS.md with all changes
• Run devtools::check() - must pass cleanly
• Update documentation: devtools::document()
• Rebuild vignettes: devtools::build_vignettes()
• Test on multiple platforms (rhub, win-builder)
• Update README if needed
• Check all examples run correctly
• Verify all URLs in documentation are valid
• Run code coverage: covr::package_coverage()
• Update copyright year if needed

CRAN Submission

• Prepare cran-comments.md
• Submit to CRAN: devtools::release()
• Monitor email for CRAN response
• Check CRAN package page after acceptance

Post-release

• Create GitHub release with tag
• Tweet/announce new version
• Update pkgdown site: pkgdown::build_site()
• Increment development version number
• Update NEWS.md with “Development version” section