Knowledge Base

Notes

• Note the difference between Free Interval in the Analysis Profile (this topic) and Nesting over a Free Interval in the Data Profile.
• Define a Free Interval in an Analysis Profile when you want to analyze the interval itself, not other dependent variables within that interval. For example, to calculate the duration of an interval.
• Define a Free Interval in a Data Profile when you want to analyze any dependent variable within the resulting track segment. For example, to calculate the average velocity of the subject in the interval.
• If a start criterion is not met in a track, EthoVision XT does not define the Free Intervals in that track.
• If a stop criterion is not met in a track, EthoVision XT does the following:
  • If you selected Ignore last intervals if incomplete, it does not define the interval.
  • If you did not select that option, it defines an interval up to the end of the track.
• Free intervals in multiple-subjects setups. A free interval is calculated for each subject separately, based on the data (dependent variables, behavior, etc.) for that subject. See Free Interval Based on Multiple Subjects.
• Free intervals and missing samples. A free interval is not interrupted if one, two, or three consecutive missing samples occur. With four or more consecutive missing samples, the current interval is interrupted and a new one starts when the Start criterion is met.
• Contiguous intervals. When two instances of a Free Interval are contiguous — for example, when the Interval Start criterion is supposed to be met immediately after the Interval Stop criterion for the previous instance is met — one sample is always excluded between the end of an instance and the start of the next instance. For example, the first instance goes from time 0 (included) to sample 100 (excluded), then from sample 101 (included) to sample 250 (excluded). Samples 100 and 250 are not included in the analysis. The reason is that the statistic used to find the start of the interval is updated one sample after the end of the previous interval.

More Details

• Free Interval Based on a Dependent Variable
• Free Interval Based on a Trial Control Event
• Free Interval Based on Hardware
• Free Interval Based on Multiple Subjects
• Examples of Free Intervals in the Analysis Profile

Source: EthoVision XT 19 Help, Noldus Information Technology