Statistics – Inter Rater Agreement (IRA) – Cohen’s Kappa


The requirement for demonstrating that an individual assessor is consistent in her/his identification of individual Tooth Development Stages (TDS) is central to the statistical validation of the clinical technique of Dental Age Estimation (DAE).

There are several methods of assessing agreement using a variety of Statistical techniques [ see Petrie and Sabin 2009]

To carry out a practical Inter Rater Agreement download the file below

[  IRA_Intra and Inter Rater Agreement (First Second Assessment) 

How often should Intra RaterAgreement be carried out?

the principle Investigator should do this at the Beginning and at the End of Establishing the Reference Data Set (RDS) using the radiographs provided under :-

[ Inter Rater Agreement (IRA) Images (DPTs) ].  Also, the investigator should select (by random numbers) 15 radiographs form their own RDS and carry IRA during the ‘middle’ of the study.

To carry out IRA select 15 DPTs using a random number procedure (See Microsoft Excel for details) and then carry out appropriate assessments and enter them into the Excel sheet you have already downloaded.  For the second assessment hide the columns of data, carry out the 2nd assessments.  Reveal the column for the first and then carry out the statistical test for Cohen’s Kappa. This will require export of the data to a statistical software package.

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