This thread is quite old, but I was wondering the same thing and, since this is the top result for the question on Google, thought this a suitable place to put my findings.
As with other things in Moodle's stats world, the answer depends on the type of stat you're requesting. I put together a table:
|
Stat |
stat1 value |
stat2 value |
|
logins |
The total number of logins made in the given period. |
The number of unique logins during that time. |
|
activity |
For each course, the number of reading actions made. |
For each course, the number of writing actions made. |
|
enrolment (not available in user stats) |
The number of enrolments on a particular course, tied to roles. |
Of those enrollees of that role, the number active in that period. |
Don't take this as read, as it is entirely through fairly vague self-investigation into the /lib/statslib.php file, but I'm pretty confident in what I found.
Again, sorry for reopening an old thread. But hopefully this can clear things up for those stuck in the future!