23 · Time & time zones

Thursday, Nov 12, 2026

Materials for this session are not published yet. They appear here before class.

Objectives

By the end of this session you can:

• Parse any date-time format, including spreadsheet serials.
• Convert between UTC and local time, daylight saving included.
• Compute intervals across time zones.
• Join time-zone geography to population for a global calculation.

What we cover

• Why clocks matter: event studies need them; survey timestamps lie in UTC; markets open across zones.
• lubridate in full; Excel serial dates; UTC vs local; daylight saving time; day-boundary drift.
• The world-clock exercise: at one UTC instant, compute local time everywhere, join population — what share of the world is likely awake?

Verification habit. Check against calendar facts you know independently — sunrise, release weekdays — and investigate the exceptions.