# Method: Open Field Test Analyzer (method version 1.0.0)

## Calculation

From each animal's tracked positions (x, y in cm, with a time stamp in seconds):

1. **Distance** = sum of the straight-line distances between consecutive positions.
2. **Session time** = last time stamp − first time stamp. **Mean velocity** = distance / session time (cm/s).
3. **Center zone** = a region centered in the arena whose area is the chosen percentage of the arena (25% by default): a rectangle with each side scaled by √(percentage / 100), or a circle with the radius scaled the same way.
4. **Center time** and **periphery time**: each interval between two positions counts toward the zone of its end point; the distance of that interval is assigned the same way. **% center time** = center time / session time × 100.
5. **Center entries** = moves from outside into the center, plus one when the first position is already in the center.
6. **Thigmotaxis index** = % of session time whose intervals end in the wall band: the outermost 10% of the arena's width and height (10% of the radius for a round arena).
7. **Time bins** repeat distance, center time and periphery time over equal parts of the session.
8. **Group statistics** per group: mean, standard deviation (n − 1 denominator) and SEM = SD / √n.

## Conventions

- The center zone includes its boundary; the wall band does not include the line at exactly 10%.
- An animal needs at least two positions with increasing time. The page leaves out an animal without them, names it after the upload, and never adds it to group statistics.
- Group statistics include every analysed animal.

## Worked examples

Three cases in `cases.json`, each worked analytically on a 40 × 40 cm arena: a straight run through the center, a position exactly on the center boundary, and an animal with a single position, which is left out (edge case).

## References

- Seibenhener ML, Wooten MC. Use of the Open Field Maze to measure locomotor and anxiety-like behavior in mice. Journal of Visualized Experiments. 2015;(96):e52434. https://doi.org/10.3791/52434

## Changes from the page before this record

- An animal with fewer than two timed positions was analysed with 0 for its velocity and percentages, which entered the group means. It is now left out and named after the upload.
- Other calculations are unchanged; the code moved to a shared module.
- The method note now says the wall band is 10% of both the width and the height (or of the radius), and that each interval counts toward the zone of its end point.