Knowledge Base

Select Intervals by Duration

Aim

To select intervals that are longer or shorter than a given duration. For example, if you observe a child, to select its behavior when the mother was present for longer than 1 minute.

Prerequisites

• You carried out your observations.
• The Data Selection window is open (Choose Analyze > Select Data > New/Open Data Profile).

Procedure

1. Insert a By Behaviors (see Select Intervals by Behaviors) or By Modifiers (see Select Intervals By Modifiers) interval box with the event of interest in the sequence between the Start box and the Results box.
2. Choose Select Intervals By Duration.
3. Specify a duration and choose Higher than, Higher or equal to, Lower than, or Lower or equal to. In the example of the child above, select Higher than 60 s.
4. Insert the box after the other interval boxes in the sequence between the Start box and the Results box.

Important: Always place the By Duration interval box after the interval boxes with the other selection criteria.

Note: If you do not combine the By Duration interval box with a By Behavior or Modifier box, you select entire observations that have that minimum or maximum duration. See Advanced Data Selections for more information on combining selection boxes.

Select Intervals by External Data

Aim

To analyze data when external data values are above or below a specific value.

Prerequisites

• Your license includes the External Data Module.
• You carried out your observations.
• The Data Selection window is open (Choose Analyze > Select Data > New/Open Data Profile).

Procedure

1. Click the button next to the appropriate By <external data signal>.
2. Specify the criteria for the external data. You can set a higher than (or equal to), or lower than (or equal to) limit. It is also possible to define a range.
3. To avoid creating intervals for external data spikes that were the result of noise, specify a Minimum interval length.
4. Insert the Interval box in the sequence between the Start box and the Results box.

Result

The upper and lower limits of the interval are fixed and based on the external data values. In the picture below, the intervals are based on a heart rate between 80 and 100 bpm. The selected intervals are shown in the white areas.

See also: The difference between Select Intervals by External Data and Select Intervals by Manual Selection with external data.

Notes on Intervals

The following notes apply to all intervals, including time bins.

Intervals and Suspending a Live Observation

If you carried out a live observation and suspended it (see Suspend an Observation), defining intervals may lead to incorrect selections. This is because suspend/resume creates extra stop and start events for that behavior. For example, if you suspended the observation when Play was active and then select an interval by Play, the resulting interval will be from the start of Play to the suspend time, not the time that you actually score the stop of Play. If this behavior is still active after you resume scoring, you will obtain a second interval from the moment the observation is resumed until the stop of Play.

Intervals and Behaviors Without Duration

It is not possible to select intervals by behaviors without duration (Point events), but you can define intervals starting or ending a defined time before or after them. See Select Intervals by Manual Selection.

Intervals and Multiple Event Logs

If an observation includes two or more event logs, an interval defined in one event log is also applied to other event logs within that observation.

Example: An interval is defined from the start of the observation to the event End of Task. FaceReader states were imported as a second event log. The interval is also applied to the FaceReader states.

If the start and stop criteria are present in more than one event log within one observation, intervals may give unexpected results. We recommend you do not use intervals in this case.

Interval Borders

See What Happens at the Interval Borders?

How Manual Intervals Are Generated

Manual Intervals in Detail

Consider the following example for selection of manual intervals. From 3 seconds after a blue tit female enters the nest until 2 seconds after the bird starts removing faeces. Set the criteria for the intervals in the following way:

Manual intervals are generated as follows:

1. The first point that matches the selection criteria for the interval start is determined.
2. The offset (before or after) specified in the Start interval at field is applied. This sets the start point of the interval.
3. The first point after the point that matches the selection criteria for the interval stop is determined.
4. The offset (before or after) specified in the Stop interval before field is applied. This sets the end point of the first interval.
5. Steps 1 to 4 are repeated until the end of the observation. The start of the next interval is always after the stop of the previous one.

Note that the four instances of In after the one at approximately 40 s are not considered for the second interval. An interval is determined by:

• The first instance of the start criteria following the previous interval.
• The first instance of the stop criteria following the start criteria.

What Happens if a Start or Stop Criterion Is Missing?

If either a start criterion is missing in the observation, or no stop criterion follows the start criterion, no interval is selected.