knit_print.dmar_tbl is the knitr print method, so a
dmar_tbl dropped into an R Markdown chunk renders as a formatted
kable (sensible rounding, whole-number sample sizes,
p-values to fixed decimals) rather than as a raw dump of doubles.
as_kable is the explicit form of the same rendering: it returns the
knitr_kable object so the caller can pipe it into
further styling or embed it in a larger document. Both reuse
format.dmar_tbl, so what a reader sees in a report matches
what they saw at the console, and neither rounds the stored numbers.
results_sentence turns a table that carries a confidence interval into the
one sentence an author puts in a results section, for example
“smd = 0.50, 95% CI [0.10, 0.90]”. It reads the estimate and its
limits from the numeric columns at full precision and formats them for the
sentence, so the reported numbers are exact to the requested decimals rather
than transcribed from the rounded console display.