SQL query which shows how long users typically spend on your site, and how that has trended over time.

segment_analysis

select
  date(session_start_timestamp) as date,
  avg(stats.duration_millis) as mean_session_duration_millis,
  approx_quantiles(stats.duration_millis, 101)[safe_offset(25)] as percentile_25,
  approx_quantiles(stats.duration_millis, 101)[safe_offset(50)] as percentile_50,
  approx_quantiles(stats.duration_millis, 101)[safe_offset(75)] as percentile_75
from
  dataform_data_sources.segment_sessions
group by
  date
order by
  date desc