`level` argument not working

[cknotz]

Please specify whether your issue is about:

• [x] a possible bug
• [ ] a question about package functionality
• [ ] a suggested code or documentation change, improvement to the code, or feature request

Hi,

I think I think the level argument in the margins_summary() function is not working as intended: Setting the confidence level to a different value than 95 has no effect on the output. It seems the argument is simply ignored. This happens with lm() and lme4::glmer(), and when using either margins_summary() or summary(margins()). Strangely, plot(margins()) works as described in the vignette -- but, contrary to what is written there, it is not possible to specify multiple confidence levels.

Hope I'm not misunderstanding something here! Many thanks in advance!

Example:

## load package
library("margins")

## code goes here
data(mtcars)

mod <- lm(mpg ~ hp, data = mtcars)

margins_summary(mod) # baseline
margins_summary(mod, level = .9) # same result
margins_summary(mod, level = .99) # same result

# just for fun
margins_summary(mod, level = 90) # same result
margins_summary(mod, level = 99) # same result
margins_summary(mod, level = .01) # same result
margins_summary(mod, level = "99") # same result

# same here
summary(margins(mod,
                level = 99))

# These work
plot(margins(mod),
     level = c(.9))
plot(margins(mod),
     level = c(.999))

This produces an error ("length of 'dimnames' [2] not equal to array extent")
plot(margins(mod),
     level = c(.999,.9))

## session info for your system
sessionInfo()
R version 4.2.2 (2022-10-31)
Platform: x86_64-apple-darwin17.0 (64-bit)
Running under: macOS Ventura 13.3.1

Matrix products: default
LAPACK: /Library/Frameworks/R.framework/Versions/4.2/Resources/lib/libRlapack.dylib

locale:
[1] en_US.UTF-8/en_US.UTF-8/en_US.UTF-8/C/en_US.UTF-8/en_US.UTF-8

attached base packages:
[1] stats     graphics  grDevices utils     datasets  methods   base     

other attached packages:
[1] margins_0.3.26

loaded via a namespace (and not attached):
 [1] Rcpp_1.0.10       rstudioapi_0.14   magrittr_2.0.3    hms_1.1.2         splines_4.2.2     MASS_7.3-58.2    
 [7] tidyselect_1.2.0  xtable_1.8-4      lattice_0.20-45   R6_2.5.1          rlang_1.1.0       minqa_1.2.5      
[13] fansi_1.0.4       dplyr_1.1.0       tools_4.2.2       grid_4.2.2        data.table_1.14.8 nlme_3.1-162     
[19] utf8_1.2.3        cli_3.6.0         ellipsis_0.3.2    lme4_1.1-31       countrycode_1.4.0 tibble_3.2.1     
[25] lifecycle_1.0.3   prediction_0.3.14 Matrix_1.5-3      nloptr_2.0.3      vctrs_0.6.1       labelled_2.10.0  
[31] glue_1.6.2        haven_2.5.1       compiler_4.2.2    pillar_1.8.1      forcats_1.0.0     generics_0.1.3   
[37] boot_1.3-28.1     pkgconfig_2.0.3