Customised summaries of vectors with appropriate defaults for longitudinal
data. The functions are prefixed with b_ to assist with autocomplete.
It uses na.rm = TRUE for all, and for calculations
involving quantiles, type = 8 and names = FALSE. Summaries include:
* b_min: The minimum
* b_max: The maximum
* b_median: The median
* b_mean: The mean
* b_q25: The 25th quantile
* b_q75: The 75th quantile
* b_range: The range
* b_range_diff: difference in range (max - min)
* b_sd: The standard deviation
* b_var: The variance
* b_mad: The mean absolute deviation
* b_iqr: The Inter-quartile range
* b_diff_var: The variance diff()
* b_diff_sd: The standard deviation of diff()
* b_diff_mean: The mean of diff()
* b_diff_median: The median of diff()
* b_diff_q25: The q25 of diff()
* b_diff_q75: The q75 of diff()