Knowledge Base

Data Analysis

In this section you find general information on how to analyze data in a conditioning test.

Data Preparation

There are three optional steps you can take to prepare your data:

• Edit the Tracks
  Choose Acquisition > Edit Tracks.
  You can fix tracking errors and swap back nose-points and tail-points that have been swapped in tracking. Normally you will not need to edit your data.
• Smooth the Tracks
  Choose Acquisition > Track Smoothing Profile.
  You can use Smoothing and/or the Minimal Distance Moved filter to remove outliers from your data and correct the distance moved calculation as a result of body wobble.
• Select Tracks and Intervals
  Choose Analysis > Data Profile.
  Select your tracks according to your independent variable values and also select parts of tracks (nesting). You can also make groups of tracks to obtain group statistics. And you can define Time bins (see data selection below).

Data Selection

Groups of Tracks

You can configure a Data Profile to compare animals that were treated with a drug with those that were treated with saline. This way you create groups of tracks to obtain group statistics for each group.

Time Bins

Using time bins means that you create time intervals of constant duration to analyze how variables change over time.

The default data selection does not specify time bins, so the behavior will be analyzed as a whole. If you define time bins and specify an interval length of, for instance, 1 minute, you can investigate whether a specific behavior changes over time.

To define time bins:

1. From the Analysis menu, select Data Profile.
2. Select New and type in Time intervals.
3. Click the Settings button on the Result box.
4. Select Results per time bin and enter the length of one interval, for example 30 s or 1 minute depending on the duration of your experiment. The data will be split in a number of intervals of the same length.
   
   When the track duration is not an exact multiple of the time bin that you set, the last time bin is shorter than the others. To ignore this time bin, select Ignore last time bin if incomplete.
5. Click OK.

If the white spotlight is aversive to the animal, the time spent in the Spot Light zone should decrease in the course of the trial. In contrast, the time interval between consecutive entries into Zone LightSpot should show an increase. Via data analysis in EthoVision XT, this can be investigated.

Analysis Profiles

Choose Analysis > Analysis Profile. If you have multiple Data Profiles, create or open a Data Profile without Results per time bin.

Below is described how to create the following analysis variables:

• In Zone — calculates how often and how long the mouse stayed in the illuminated zone.
• Trial Control State "Interval in Spot Light Zone" — measures the time elapsed until the mouse enters the light spot again, for each repeat of the learning routine.
• Trial Control State "Duration Light On" — measures the time that the mouse stays in the light spot in each repeat of the learning routine.
• Trial Control Event "Frequency Light On" — measures the number of times that the light is switched on.

In Zone

1. Select New and type in In Zone. The new Analysis Profile contains the default dependent variables Distance moved and Velocity. Click on a dependent variable and press Delete to remove it.
2. Click the Add button next to In Zone.
   1. Under In the following zones, select Spot Light. Under From following body points, select both Nose-point and Center-point and select All selected points from the list at the bottom.
   2. In the Trial Statistics tab, select Mean, Frequency and Duration.
   3. Select additional statistics in the Group Statistics tab, if you created groups of tracks in your Data Profile.
   4. Click OK.

Trial Control

1. Click the Add button next to Trial Control State.
   1. From the From Element list, select Rule: Anxiety Test. From the From Event list, select becomes active.
   2. From the to Element list, select Action: Light on. From the to Event list, select becomes active.
   3. Select Calculate statistics per interval, for consecutive intervals.
   4. In the Trial Statistics tab, select Cumulative duration.
   5. Select additional statistics in the Group Statistics tab, if you created groups of tracks in your Data Profile. Then click OK.
   6. Right-click Trial Control State, select Rename and type Interval in Spot Light zone.
2. Click the Add button next to Trial Control State.
   1. From the From Element list, select Action: White Light On. From the From Event list, select becomes active.
   2. From the to Element list, select Action: White Light off. From the to Event list, select becomes active.
   3. Select Calculate statistics per interval, for consecutive intervals.
   4. In the Trial Statistics tab, select Cumulative duration.
   5. Select additional statistics in the Group Statistics tab, if you created groups of tracks in your Data Profile. Then click OK.
   6. Right-click Trial Control State, select Rename and type Duration Light on.
3. Click the Add button next to Trial Control Event.
   1. From the From Element list, select Action: White Light On.
   2. From the From Event list, select becomes active.
   3. In the Trial Statistics tab, select Frequency.
   4. Select additional statistics in the Group Statistics tab, if you created groups of tracks in your Data Profile. Then click OK.
   5. Right-click Trial Control Event, select Rename and type Frequency light on.

More Options with the Free Interval Function

The Free interval function in the Data Profile and in the Analysis Profile allows you to extend the possibilities to define the start and the end of intervals. For example, from the time a stimulus event occurs, to 10 seconds after that event.

1. Choose Analysis > Analysis Profile.
2. Under Miscellaneous, click next to Free Interval.

For details, search the EthoVision XT Help for Free interval.

Integrated Visualization

When you Plot Integrated Data, the video file and the Time Event Plot are displayed. The Time Event Plot displays the variables of the active Analysis Profile.

The Integrated Visualization for an Analysis Profile containing Trial Control variables displays the Time Event Plot showing (from top to bottom) Duration Light on, Frequency Light on, and Interval in LightSpot, all for each arena separately. The vertical line shows the current position in the Time Event Plot and the video window displays the corresponding frame in the video.

Source: EthoVision XT 18 - Application Manual, Noldus Information Technology