[[ml-calendars]]
=== Calendars and Scheduled Events

Sometimes there are periods when you expect unusual activity to take place,
such as bank holidays, "Black Friday", or planned system outages. If you
identify these events in advance, no anomalies are generated during that period.
The {ml} model is not ill-affected and you do not receive spurious results.

You can create calendars and scheduled events in the **Settings** pane on the
**Machine Learning** page in {kib} or by using {ref}/ml-apis.html[{ml} APIs].

A scheduled event must have a start time, end time, and description. In general,
scheduled events are short in duration (typically lasting from a few hours to a
day) and occur infrequently. If you have regularly occurring events, such as
weekly maintenance periods, you do not need to create scheduled events for these
circumstances; they are already handled by the {ml} analytics.

You can identify zero or more scheduled events in a calendar. Jobs can then
subscribe to calendars and the {ml} analytics handle all subsequent scheduled
events appropriately.

If you want to add multiple scheduled events at once, you can import an
iCalendar (`.ics`) file in {kib} or a JSON file in the
{ref}/ml-post-calendar-event.html[add events to calendar API].

[NOTE]
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* You must identify scheduled events before your job analyzes the data for that
time period. Machine learning results are not updated retroactively.
* If your iCalendar file contains recurring events, only the first occurrence is
imported.
* Bucket results are generated during scheduled events but they have an
anomaly score of zero. For more information about bucket results, see
{ref}/ml-results-resource.html[Results Resources].
* If you use long or frequent scheduled events, it might take longer for the
{ml} analytics to learn to model your data and some anomalous behavior might be
missed.

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