I suggest you add a 'summarize by' sort of sumtab thing:

[daaronr]

tabsums <- function(df, yvar, xvar){
    df %>% ungroup() %>%
        dplyr::group_by({{xvar}}) %>%
        dplyr::select({{yvar}}, {{xvar}}) %>%
        dplyr::summarise(
            nonmissing = sum(!is.na({{yvar}})),
            mean = mean({{yvar}}, na.rm = TRUE),
            sd = sd({{yvar}}, na.rm = TRUE)
        )
}

works pretty well for me