Formatting inconsistency in estimate_grouplevel() with a categorical predictor

[jmgirard]

When extracting random effects from an lmer model using estimate_grouplevel(), the formatting of factor levels in the Parameter column is inconsistent. The first instance of a factor's random slope gets cleaned up nicely (e.g., treatment [1]), but all subsequent rows for that same parameter revert to the raw lme4 naming convention (e.g., treatment1).

library(lme4)
#> Loading required package: Matrix
library(easystats)
#> # Attaching packages: easystats 0.7.5
#> ✔ bayestestR  0.17.0   ✔ correlation 0.8.8 
#> ✔ datawizard  1.3.0    ✔ effectsize  1.0.1 
#> ✔ insight     1.4.6    ✔ modelbased  0.14.0
#> ✔ performance 0.16.0   ✔ parameters  0.28.3
#> ✔ report      0.6.3    ✔ see         0.13.0

# Prepare built-in data with a 0/1 categorical predictor
dat <- sleepstudy |> 
  dplyr::mutate(treatment = factor(ifelse(Days > 4, "1", "0")))

# Fit a model with a random slope for the factor
fit <- lmer(Reaction ~ treatment + (1 + treatment | Subject), data = dat)

# Extract random effects
# Notice Subject 308 gets "treatment [1]" while 309+ get "treatment1"
estimate_grouplevel(fit, type = "random")
#> Group   | Level | Parameter     | Coefficient |    SE |           95% CI
#> ------------------------------------------------------------------------
#> Subject | 308   | (Intercept)   |       21.70 | 10.38 | [  1.36,  42.04]
#> Subject | 308   | treatment [1] |       42.41 | 14.18 | [ 14.61,  70.20]
#> Subject | 309   | (Intercept)   |      -55.24 | 10.38 | [-75.58, -34.90]
#> Subject | 309   | treatment1    |      -44.64 | 14.18 | [-72.44, -16.85]
#> Subject | 310   | (Intercept)   |      -45.89 | 10.38 | [-66.23, -25.55]
#> Subject | 310   | treatment1    |      -33.27 | 14.18 | [-61.06,  -5.48]
#> Subject | 330   | (Intercept)   |       11.64 | 10.38 | [ -8.70,  31.98]
#> Subject | 330   | treatment1    |      -19.84 | 14.18 | [-47.64,   7.95]
#> Subject | 331   | (Intercept)   |       16.66 | 10.38 | [ -3.68,  37.00]
#> Subject | 331   | treatment1    |      -18.86 | 14.18 | [-46.66,   8.93]
#> Subject | 332   | (Intercept)   |        4.69 | 10.38 | [-15.65,  25.03]
#> Subject | 332   | treatment1    |        7.72 | 14.18 | [-20.08,  35.51]
#> Subject | 333   | (Intercept)   |       13.59 | 10.38 | [ -6.75,  33.93]
#> Subject | 333   | treatment1    |        4.51 | 14.18 | [-23.28,  32.31]
#> Subject | 334   | (Intercept)   |       -4.43 | 10.38 | [-24.77,  15.91]
#> Subject | 334   | treatment1    |        4.34 | 14.18 | [-23.45,  32.14]
#> Subject | 335   | (Intercept)   |      -22.23 | 10.38 | [-42.57,  -1.89]
#> Subject | 335   | treatment1    |      -51.99 | 14.18 | [-79.78, -24.19]
#> Subject | 337   | (Intercept)   |       49.50 | 10.38 | [ 29.16,  69.84]
#> Subject | 337   | treatment1    |       45.91 | 14.18 | [ 18.11,  73.70]
#> Subject | 349   | (Intercept)   |      -20.23 | 10.38 | [-40.58,   0.11]
#> Subject | 349   | treatment1    |        1.49 | 14.18 | [-26.30,  29.29]
#> Subject | 350   | (Intercept)   |       -1.37 | 10.38 | [-21.72,  18.97]
#> Subject | 350   | treatment1    |       38.02 | 14.18 | [ 10.22,  65.81]
#> Subject | 351   | (Intercept)   |       -1.65 | 10.38 | [-21.99,  18.69]
#> Subject | 351   | treatment1    |      -14.84 | 14.18 | [-42.63,  12.96]
#> Subject | 352   | (Intercept)   |       28.95 | 10.38 | [  8.61,  49.29]
#> Subject | 352   | treatment1    |       12.62 | 14.18 | [-15.17,  40.42]
#> Subject | 369   | (Intercept)   |        5.29 | 10.38 | [-15.05,  25.63]
#> Subject | 369   | treatment1    |        3.26 | 14.18 | [-24.53,  31.06]
#> Subject | 370   | (Intercept)   |      -15.14 | 10.38 | [-35.48,   5.20]
#> Subject | 370   | treatment1    |       24.26 | 14.18 | [ -3.53,  52.06]
#> Subject | 371   | (Intercept)   |        0.73 | 10.38 | [-19.61,  21.07]
#> Subject | 371   | treatment1    |       -9.96 | 14.18 | [-37.75,  17.84]
#> Subject | 372   | (Intercept)   |       13.44 | 10.38 | [ -6.90,  33.78]
#> Subject | 372   | treatment1    |        8.86 | 14.18 | [-18.94,  36.65]

^{Created on 2026-03-01 with reprex v2.1.1}

Expected Behavior

The Parameter column should apply the factor [level] formatting consistently across all grouping levels rather than just the first one.