Typically the correlations between two human scorers reach values between 0.80 and 0.90. Very skilled well-trained scorers may even reach 0.93 or 0.95. Machine scores typically correlate with expert human ratings at the same level as two human raters do. Machine scores correlate better with well trained expert human scorers, than with human scorers with low interrater agreement. Furthermore machine scoring is trained on a large pool of human scorers, more than 250 human scorers in the case of PTE Academic. This means that the machine scores are in fact closer to the scores from the ideal human rater than the scores from individual human raters, or even pairs of human raters.