# add_n.tbl_summary() works

    Code
      as.data.frame(add_n(tbl_summary(trial, include = c(age, grade, response)),
      statistic = "{N_nonmiss} / {N_obs}", footnote = TRUE, last = TRUE))
    Output
        **Characteristic** **N = 200**     **N**
      1                Age 47 (38, 57) 189 / 200
      2            Unknown          11      <NA>
      3              Grade        <NA> 200 / 200
      4                  I    68 (34%)      <NA>
      5                 II    68 (34%)      <NA>
      6                III    64 (32%)      <NA>
      7     Tumor Response    61 (32%) 193 / 200
      8            Unknown           7      <NA>

# add_n.tbl_summary(statistic) error messaging

    Code
      add_n(tbl_summary(trial, by = trt, include = c(trt, age, grade, response)),
      statistic = "no_curlies")
    Condition
      Error in `add_n()`:
      ! No glue elements found in the `statistic` argument ("no_curlies").
      i Do you need to wrap the statistic name in curly brackets, e.g. "{N_nonmiss}"?

---

    Code
      add_n(tbl_summary(trial, by = trt, include = c(trt, age, grade, response)),
      statistic = "{not_a_stat}")
    Condition
      Error in `add_n()`:
      ! The following statistics are not valid for the `statistic` argument: "not_a_stat".
      i Select from "N_obs", "N_miss", "N_nonmiss", "p_miss", and "p_nonmiss".

