in Data-->statistics-->Descriptive Statistics, please add FIRST and THIRD Quartile to the list of reported statistical measures.
For this the relevant function =QUARTILE() already exists in Calc
Eike/Winfried: I found a start here to implement it:
but should ux team give its advice about it?
Meanwhile, I put it as new enhancement.
Tomaž Vajngerl committed a patch related to this issue.
It has been pushed to "master":
fdo#81801 add first and third quartile to "Descriptive Statistics"
It will be available in 4.4.0.
The patch should be included in the daily builds available at
http://dev-builds.libreoffice.org/daily/ in the next 24-48 hours. More
information about daily builds can be found at:
Affected users are encouraged to test the fix and report feedback.