# 19 Introducing confidence intervals

One type of
research question
is the
estimation-type RQ,
when the precision of a *statistic* is of interest.
In this Part,
answering estimation-type RQs is discussed for:

- Descriptive RQs: Chaps. 20 to 23;
- Relational or interventional RQs with a
*comparison*: Chaps. 24 and 25.

Answering estimation-type RQs for relational or interventional RQs with a
*connection* is explored later
(Chaps. 35 and 36).

The precision of statistics influences decision-type RQ too: when statistics precisely estimate parameters, making decisions about parameters is easier.

The previous chapters, where tools for describing sampling variation were introduced, are used in this part to understand the precision of statistics.