FAQ: How can I recover the accuracy of a participant's calibration?

[Sam]

After a validation is completed, its results are displayed in the bottom right-hand corner of the Host PC screen. This information is also permanently saved to the EyeLink Data File (.edf) recorded during that session.

In our analysis software, Data Viewer, the validation results can be output in a Trial Report, by including the VALIDATION_RESULT_LEFT/RIGHT_EYE Variables.

   

The Validation results can also be extracted by converting the EDF file to ASCII:

• Convert the File: Convert the .edf file to an ASCII text file (.asc). You can do this using the VisualEDF2ASC utility, which is included with the free EyeLink Data Viewer software.
  
• Find the Validation Data: Open the converted .asc text file in any text editor. Search for lines containing !CAL VALIDATION, which are typically found near the beginning of the file. The validation message in the data file will look similar to this:
  

  MSG 8017110 !CAL VALIDATION HV9 R RIGHT GOOD ERROR 0.43 avg. 0.63 max OFFSET 0.36 deg. -9.3,12.6 pix.

  In this example:
  • HV9: Indicates a 9-point calibration model was used.
    
  • R: The eye/s tracked
    
  • RIGHT GOOD ERROR 0.43 avg. 0.63 max: This is the key data, showing a "Good" validation for the right eye with an average error of 0.43° and a maximum error of 0.63°.
    Note: if a binocular validation was performed you will have separate results for the left and right eye reported independently.
    

If you performed multiple validations during the session, there will be several !CAL VALIDATION messages in the file. Be sure to use the results from the final, successful validation for your analysis.