Anytime-valid control charts with e-detectors.
edetect answers one question: how do I monitor a process for a change and raise an alarm with a guaranteed false-alarm rate, without assuming a parametric model for the process before or after the change? It implements e-detectors (Shin, Ramdas & Rinaldo, 2024): nonparametric, anytime-valid analogues of the CUSUM and Shiryaev–Roberts charts, built from e-values for bounded, sub-Gaussian, Bernoulli or Poisson observations, with a guaranteed average run length (ARL) to a false alarm under every distribution in the declared pre-change class.
The package follows the Phase I / Phase II workflow of shewhartr and the result-contract conventions of seqbench: every alarm (or its absence) comes with what was assumed, how the detector was built and what was observed.
Installation
# install.packages("pak")
pak::pak("castlaboratory/edetect")Example
A bounded loss whose mean should stay at 0.5 rises after 60 observations.
library(edetect)
set.seed(1)
x <- c(runif(60, 0.3, 0.7), runif(60, 0.5, 0.9))
chart <- edetect_x(x, bounds = c(0, 1), center = 0.5, arl = 370, direction = "up")
#> Warning: Alarm at t = 71; 49 later observations were not consumed.
edetect_alarm(chart)
#> # A tibble: 1 × 6
#> alarm alarm_time evidence threshold change_estimate n_observed
#> <lgl> <int> <dbl> <dbl> <int> <int>
#> 1 TRUE 71 387. 370 58 71
autoplot(chart)The same engine drives the attribute charts and a regression chart:
edetect_p(defects, n = 100, center = 0.02, arl = 370) # proportion nonconforming
edetect_c(counts, phase1 = counts_in_control, arl = 370) # counts per unit
edetect_u(counts, n = exposure, center = 1.5, arl = 370) # counts per unit exposure
edetect_regression(y ~ x, phase1 = d1, phase2 = d2, arl = 370) # residuals of a Phase I modelLower-level functions give full control: edetect_design() fixes the pre-change class, the direction, the detector type (SR or CUSUM) and the mixture of post-change shifts; edetect_init() and edetect_update() run it one observation at a time; edetect_report(), tidy(), glance() and autoplot() read the result; edetect_arl() simulates run lengths and detection delays of a design. The vignettes on the package site work through the industrial datasets of shewhartr: tablet weights, bottle filling, insurance claims, solder defects and an oven with drift.
Guarantee
For a design with target arl, every pre-change distribution in the declared class gives an expected time to a false alarm of at least arl, and a probability of a false alarm by any time t of at most t / arl (Ramdas, 2026). The classes are bounded (known bounds, nothing else), sub-Gaussian (declared scale), Bernoulli (p chart; dependence within a subgroup allowed given the conditional probabilities) and Poisson (c and u charts; no overdispersion). The price is detection delay, which the mixture of shifts and edetect_arl() let you measure before monitoring.
Related software
edetect is not a general change-point library. For classical charts calibrated by simulation see shewhartr and qcc; for ARL computation of CUSUM/EWMA charts see spc; for nonparametric sequential change-point models see cpm. No package implementing e-detectors was found on CRAN or PyPI (checked 2026-09-25 and 2026-10-10).