For a single dataframe, the tibble returned contains the columns:
col_name, a character vector containing column names of df1.
cnt, an integer vector containing the number of missing values by
column.
pcnt, the percentage of records in each columns that is missing.
For a pair of dataframes, the tibble returned contains the columns:
col_name, the name of the columns occurring in either df1 or df2.
cnt_1, cnt_2, a pair of integer vectors containing counts of missing entries
for each column in df1 and df2.
pcnt_1, pcnt_2, a pair of columns containing percentage of missing entries
for each column in df1 and df2.
p_value, the p-value associated with test of equivalence of rates of missingness. Small
values indicate evidence that the rate of missingness differs for a column occurring
in both df1 and df2.
For a grouped dataframe, the tibble returned is as for a single dataframe, but where
the first k columns are the grouping columns. There will be as many rows in the result
as there are unique combinations of the grouping variables.