Tracks Directness 
µm 
Directness is a measure of the straightness of the cell track trajectory. It is calculated
by comparing the Euclidean distance and the accumulated distance. A directness of 1.0 equals a
straightline migration.

Accumulated Distance 
µm 
Accumulated distance is the total distance covered by a cell whether it ran in circles or a straight line.

Accumulated Euclidean Distance 
µm 
The sum of all cells' Euclidean Distances in the well.

Euclidean Distance 
µm/time unit 
A vector of a cell track end position less the cell track start position.
If a cell ends where it starts, its euclidean distance will be zero.

Cell Speed 
µm/time unit 
Speed is a change in distance divided by change in time. This requires a start and end time for the calculations.
We define speed over Evaluation Interval. We define speed as a changing value over time.
A cell may move fast then stop and rest. It may move in circles and end where it starts. So it may
have a high speed but show no chemotaxis directionality because it ends where it starts.

Cell Velocity 
µm/time unit 
Velocity is change in distance divided by change in time where the distance is the Euclidean Distance
and the time is the entire track duration. It is an indicator of chemotatic effect.

Center of Mass Displacement 
µm 
Center of Mass Displacement (CoM) is the average Euclidean Distance for the x and y axis  CoMx and CoMy correspondingly.
This is a very consise indication of the average Direction and magnitude of the overall cell movement in a well or condition group.
The CoM report polar chart shows the average direction and magnitude of center of mass displacement for cells in the well or condition group.
The CoM bar chart shows the magnitude of the center of mass displacement average for all cells in the well or condition group.

CoM Displacement Magnitudes 
µm 
A scalar that represents the magnitude of the CoM displacements, not the direction.

Endpoint Tracking Chart 
µm 
... 
Evaluation Interval 
time unit 
Speed and accumulated distance are measured on time intervals. This time interval can be the same as the frame time,
or, it can be set to a number greater than the frame time. The Frame time is an experiment setting provided by user.

Forward Migration Index 
% 
Indication of change in the center of mass (CoM) on the X and Y axes. It is the average of
the difference in starting points and ending points of all cell tracks. The values are normalized
by dividing the Accumulated Distance. This is useful to indicate which axes have the highest
percentage of the total CoM displacement. If the chemical gradient is on the Y axis, then the FMIy
should be greater to indicate chemotactic effect.

Mean Cell Speed Excluding NonMoving 
µm/time unit 
Cell speed excluding nonmoving cells. Nonmoving cells are those that do not meet the thresholds set with
Minimum Track Duration or Movement Threshold experiment settings.

Mean Cell Speed Including NonMoving 
µm/time unit 
Cell speed including all cells.

Mean Cell Velocity Excluding NonMoving 
µm/time unit 
Cell velocitiy excluding nonmoving cells. Nonmoving cells are those that do not meet the thresholds set with
Minimum Track Duration or Movement Threshold experiment settings.

Mean Cell Velocity Including NonMoving 
µm/time unit 
Cell velocity including all cells.

Mean Euclidean Distance 
µm 
The mean of all cells' Euclidean Distance in the well.

Mean Square Displacement 
µm² 
This implementation of Mean Square Displacement has been borrowed from the study of the dynamics of molecules and here applied to the dynamics of cells.
The dynamics of molecules (cells) has them colliding and recolliding with each other, and observation of the trajectory
of any given molecule (cell) will find that it meanders erratically and randomly through the available volume.
Although there is no directed motion, a molecule (cell) will not remain indefinitely in the vicinity of its present position.
The question arises, "how far will a molecule (cell) travel in a given time interval?" This matter is relevant to transport
processes in the material, most notably (but not only) the rate of diffusion.
The mean square displacement (msd) is a measure of the average distance a molecule (cell) travels. It is defined
In this equation, r_{i}(t)r_{i}(0) is the (vector) distance traveled by molecule (cell) i
over some time interval of length t, and the squared magnitude of this vector is averaged (as indicated by the
angle brackets) over many such time intervals. Often this quantity is averaged also over all molecules (cell) in the system,
summing i from 1 to N and dividing by N.

Minimum Track Duration 
time unit 
Track must have a time duration greater or equal to this experiment setting to be accounted by Valid Tracks metric
and to be considered a moving cell. This is an experiment setting provided by user.

Movement Threshold 
µm 
A cell must move more than this threshold to be considered as moving cell in any time interval.
If the cell movement is less than this value in any time interval, cell movement will
not be counted as the Cell Speed or Accumulated Distance. The value can be used to prevent
noisy signals from stationary cells. This is an experiment setting provided by user.

Rayleigh test 

Rayleigh test is a statistical test for the uniformity of a circular distribution of points (cell endpoints).
With p < 0.05, the null hypothosis (uniformity) is rejected, indicating a chemotaxis effect. Like all statistical tests, this one strongly
depends on the number of analyzed cells.

Report Time Interval (RTI) 
time unit 
Dynamically calculated based on the experiment setting Time between images value and total experiment duration. Can be one of the following: minutes, seconds, hours, days. 
Time Point 
time unit 
Moment in time based on setting RTI value. Starts from 0 which corresponds to the first image of the experiment recording. 
Total Tracks 
ea 
The total number of tracks discovered through all time intervals. 
Total Valid Tracks 
ea 
The total number of tracks discovered through all time intervals that meet the Minimum Track Duration requirement. 
Track Length 
µm 
Track Length is sum of distance in each time inteval. 
Tracks Ending In Interval 
ea 
The number of tracks lost at time interval.

Tracks In Interval 
ea 
The number of active cell tracks at the given time interval. If cells die or leave the field of view, this
number will drop. If cells replicate or enter the field of view, this number will increase.
Tracks can also be lost due to tracking errors. If this image quality is low (out of focus areas for example),
this can lead to errors. If the user observes an excessive error rate, this should be reported to
MetaVi Labs Support for making improvement.

Tracks Starting In Interval 
ea 
The number of new tracks obeserved in time interval.

Track Trajectory 

Track path with a normalized origin. 
VisibleT cells in Interval 

The number of T cells observed at each time point. Observered T cells may not be actual T cells. The cell density and aggregation can effect the AI accuracy. 
T Cells in Interval Excluding Short Tracks (exclude < ?? hours) 

The number of T cells observed at each time point, excluding T cell tracks that had a duration less than the specified time. Observered T cells may not be actual T cells. The cell density and aggregation can effect the AI accuracy. 
Absolute Number Living Target Cells in Interval 

The number of living target cells observed at each time point. Observered Pathogens may not be actual Pathogens. The cell density and aggregation can effect the AI accuracy. 
Dead or Disappeared Pathogens Cells 

The total of the visible pathogens tagged as dead by AI plus pathogens that were visible in previous intervals but are now not visible (excluding those moved out of frame). 
Ratio of T cells to Pathogens in Interval 

The number of T cells divided by the number of Pathogens in the time interval. Includes all T cell tracks existing in the interval. 
Absolute Number Synapses in Interval (Excluding Short Tracks) 

An estimate of the number of synapses in the time interval (excludes short T cell tracks). A synapse is decudeced by observing a T cell within a 20 µm distance of a Pathogens for 30 minutes or longer. 
Percent of T cells in Synapse in Interval (Excluding Short Tracks) 

The number of estimated T cell synapses divided by the total obeserved T cells at the time internval (excludes short T cell tracks). Because a T cell can be in close proxcimity to more than one cancer cell, it can appear to be in two synapses at once. So this measurement can be affected by high cell density. 
Histogram of Attacks as Ratio of Total T cells (Excluding Short Tracks) 

The xaxis is the number of attacks. The yaxis is the percent of T cells that made the given number of attacks (excludes short T cell tracks). 
Histogram of Effective Attacks as Ratio of Total T cells (Excluding Short Tracks) 

Effective attack is an attack that ended in cell death of the target. Cell death is deduced by the loss of the visible signature of a living cell, i.e. by morphological appearance. The xaxis is the number of effective attacks. The yaxis is the percent of T cells that made the given number of effective attacks (excludes short T cell tracks). 
Killing Efficiency (KE) 

Killing Efficiency (KE) is a metric that combines the time required to kill a population of target cells and also the ratio of effector cells to target cells.
Higher efficiency means less time and fewer effectors are required. Lower efficiency effector cells require either more time or more effectors relative to the number of targets.
The equation for KE is:
KE = (KETimeFactor / KillingDuration) * (TargetToEffectorRatio)
Where KETimeFactor is set on an assay basis as 4 hours to 12 hours. This is the time basis for an ideal KE killing duration.
KillingDuration is measured on the cytotoxicty chart to be the time from start of killing to the peak killing point.
TargetToEffectorRatio is the accumulated number of target cells killed by the timepoint of peak killing relative to the initial effector count (at time zero).
