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shewhartr 1.3.0 (development version)

New chart family

The multivariate side of the package now has the natural pair of memory-based charts. Both follow the calibrate() / monitor() Phase I / Phase II workflow.

• shewhart_mewma() — Multivariate Exponentially Weighted Moving Average (Lowry, Woodall, Champ & Rigdon 1992). The multivariate analogue of shewhart_ewma(): joint monitoring of p > 1 correlated variables for small persistent shifts in the vector mean. Time-varying and steady-state covariance both supported. Decision interval h calibrated by lookup in Prabhu & Runger
  1997. Table 3 (ARL_0 ~ 200).
• shewhart_mcusum() — Multivariate CUSUM (Crosier 1988). The multivariate analogue of shewhart_cusum(). Uses Crosier’s shrinkage operator: at each step the cumulative vector is shrunk towards zero by k / C_i where C_i is its Mahalanobis norm; if the norm falls below k, the cumulative vector resets to zero. Decision interval h calibrated by lookup in Crosier (1988) Table 1 for k = 0.5, ARL_0 ~ 200, p = 2..10. Phase II monitoring continues from the calibration’s final S vector (Crosier 1988 §5).

Visual identity

• Every autoplot() method now uses shewhart_palette() and shewhart_theme(), so plots from any chart family share the same editorial look (off-white surface, single horizontal grid, bold left-aligned title, sequential phase palette, hollow firebrick rings on out-of-control points). Out-of-control marks centralised in a new internal violation_layers() helper, sized at halo 1.7 / ring 1.4 / stroke 0.7.
• Regression chart legend title is now plural and bold (“Phases” / “Fases”) and uses localised Phase 0, Phase 1, … labels via the phase_n and new legend_phases locale entries.
• The arl-simulation vignette’s hand-rolled chart was using theme_minimal() with default ggplot2 colours; now uses shewhart_theme() and the package palette so it matches the rest.

Bug fixes / hygiene

• Three U+2014 em-dash characters in R/autoplot.R (two comments, one string literal) replaced with ASCII alternatives or the — escape so R CMD check no longer warns about non-ASCII source.

shewhartr 1.2.0

This release closes the remaining items from dev/ROADMAP.md §11 that were left for after v1.1: a plotly bridge and external numerical validation against the long-established qcc package.

Interactive plots: as_plotly()

• New generic as_plotly() with a shewhart_chart method that converts any chart into an interactive plotly figure. For two-panel charts (I-MR, X̄-R, X̄-S) the helper produces a plotly::subplot() with a synchronised x-axis. plotly is in Suggests, so it is only loaded on demand.
• The tooltip argument is forwarded to plotly::ggplotly() for full control of what hover boxes display.

Validation against qcc

• New tests/testthat/test-vs-qcc.R (skipped silently if qcc is not installed) compares the limits computed by shewhartr to the reference values from the qcc package on its canonical example datasets — pistonrings for the variables charts, orangejuice for p / np, circuit for c. Every centre line and 3-sigma limit agrees with qcc to within 1e-3 absolute tolerance.

Test hygiene

• test-monitor.R no longer triggers the (correct) “small c_bar” cli_warn from chart-c.R: the test data uses lambda = 12 so the normal approximation is well-behaved. The 1-warning warning in devtools::test() is gone; the suite is now FAIL 0 / WARN 0.

shewhartr 1.1.0

This release closes most of the items left open in dev/ROADMAP.md §11.

New chart family: multivariate

• shewhart_hotelling() is the package’s first multivariate chart — a Hotelling T² chart for jointly monitoring p > 1 correlated variables. Both individual observations (subgroup = NULL) and subgrouped data are supported, with the appropriate exact Phase I limits (Beta for individuals, F for subgroups) and the slightly wider Phase II limits as derived in Tracy, Young & Mason (1992) and Montgomery (2019, Chapter 11). The implementation follows Mason & Young (2002).
• The augmented tibble carries the T² statistic per row, its decomposition by variable (the contribution of each variable to the alarm — useful when T² signals but no univariate chart does), and a logical flag against the appropriate chart-level UCL.
• Vignette multivariate-charts walks through the standard worked example: a chemical process with three correlated quality characteristics, showing how the multivariate chart catches a correlation-breaking shift that any of the three univariate charts would miss.

Phase II for EWMA and CUSUM

• monitor() now dispatches to monitor_ewma() and monitor_cusum() (R/calibrate.R), so the calibrate(..., chart = "ewma") / monitor(new_data, calib) workflow now works uniformly across every chart in the package — not just the Shewhart-style ones.
• calibrate() accepts the new keys "ewma", "cusum", "hotelling".

Bug fixes

• SSgompertzDummy self-starter is more robust: starting values for b2 and b3 are now derived from the cumulative-mid-point heuristic rather than hard-coded constants, fixing the convergence failure with typical sample sizes that previously required \dontrun{} in the example.

shewhartr 1.0.0

This release is a comprehensive reposition of the package. The original (v0.1.x, distributed as Shewhart) was COVID-focused and provided a single function family for regression-based control charts. v1.0.0 is a full general-purpose SPC toolkit while preserving the regression-chart speciality that motivated the package.

Rename. As part of the reposition, the package has been renamed Shewhart → shewhartr to follow modern lowercase R-package conventions and to free the name “Shewhart” for the methodology in text and documentation. Update existing code with library(shewhartr) (formerly library(Shewhart)).

The API has been substantially redesigned. Existing scripts written against v0.1.x will not run unchanged.

Repositioning

• The package is now a general-purpose SPC toolkit. The COVID-19 use case is preserved as a vignette case study (covid-recife), not as the organising principle.
• The package competes in the same space as qcc and qicharts2, and emphasises five differentiators: tidyverse-native API, broom integration, regression-based charts as a first-class citizen, embedded methodology (ARL, Box-Cox, runs tests), and an explicit Phase I / Phase II workflow.

New chart families

• Variables: shewhart_i_mr(), shewhart_xbar_r(), shewhart_xbar_s().
• Attributes: shewhart_p(), shewhart_np(), shewhart_c(), shewhart_u(). The c and u charts accept limits = "poisson" for exact Poisson quantile limits rather than the normal approximation.
• The flagship shewhart_regression() replaces the old shewhart() function with a cleaner API, an extensible model menu (auto, linear, log, loglog, gompertz, logistic, plus user formulas), automatic phase detection via configurable runs rules, and proper handling of irregular time grids.
• Memory-based charts: shewhart_ewma() (Roberts 1959) for the Exponentially Weighted Moving Average chart, with both time-varying and steady-state limits, and shewhart_cusum() (Page 1954) for the two-sided tabular CUSUM chart with configurable reference value k and decision interval h. Both fit in the same S3 / broom / autoplot pipeline as the classical charts.

New methodology

• shewhart_runs() implements the eight Nelson rules (1984, 1985) plus a Western Electric “7 in a row” variant for backward compatibility. Rule sets are user-configurable on every chart.
• shewhart_arl() performs Monte Carlo Average Run Length simulation for arbitrary rule combinations.
• shewhart_box_cox() returns the profile log-likelihood, optimal lambda, and 95% CI in the Box & Cox (1964) tradition.
• shewhart_diagnostics() produces a five-panel Tukey-style residual diagnostic display.
• shewhart_capability() computes Cp/Cpk/Pp/Ppk with bootstrap confidence intervals.
• calibrate() and monitor() provide an explicit Phase I / Phase II workflow.

S3 / broom integration

• All charts return an S3 object of class shewhart_chart with a specific subclass.
• print(), summary(), autoplot(), tidy(), glance() and augment() methods are provided for every chart type.

Internationalisation

• All user-facing chart functions accept a locale argument ("en", "pt", "es", "fr") that controls plot labels and informative messages. Validation errors remain in English to facilitate cross-user debugging.

Developer-facing changes

• Depends collapsed: the package no longer depends on the entire tidyverse meta-package or on tibbletime/pals/scales. The new Imports are minimal and explicit.
• plotly moved to Suggests to avoid pulling a heavy dependency for users who don’t need interactive plots.
• All input validation uses cli::cli_abort() / cli::cli_warn() with multi-line, informative messages.
• .onAttach() no longer prints a banner.
• New data-raw/build_all.R script generates six synthetic datasets (tablet_weight, bottle_fill, pcb_solder, claims_p, temperature_drift, bacterial_growth).
• New documentation site built with pkgdown at https://castlaboratory.github.io/shewhartr/. Ten topical articles, including a dedicated memory-based-charts vignette covering EWMA, CUSUM and the trade-offs versus Shewhart-style charts.

Breaking changes (full list)

• shewhart() (the plotting function) has been removed. Use shewhart_regression() followed by autoplot().
• shewhart_fit() is no longer exported. Use shewhart_regression().
• shewhart_model() is no longer exported. Use shewhart_regression().
• shewhart_7points() is no longer exported. Use shewhart_runs(rule = "we_seven_same") for the same behaviour, or the recommended shewhart_runs(rule = "nelson_2_nine_same").
• The default phase-detection rule is now Nelson 2 (9 points same side; ARL_0 ~ 256), not the legacy 7-points-same-side (ARL_0 ~ 64). Pass phase_rule = "we_seven_same" to recover the old behaviour.
• The package banner printed on .onAttach() has been removed.
• All output column names follow broom-style with a leading . (.fitted, .upper, .lower, .flag_*).

These binaries (installable software) and packages are in development.
They may not be fully stable and should be used with caution. We make no claims about them.