Average difference and 95% limits of agreement between the reference method and the field methods before and after conversion to the IS. Nineteen field methods have been submitted to the validation procedure for their current analytical system. (A) Before conversion, the average difference between each field method and the reference method as represented by the diamonds ranged from 7.7-fold lower to 8.1-fold higher. A difference of 1.0 indicates no difference between the average of the BCR-ABL values. The bars above and below the average difference define the 95% limits of agreement for that field method. (B) After conversion, the average differences were within plus or minus 1.2-fold for most field methods. However, the 95% limits of agreement varied.