The first judge is a lot less strict than the second judge, who gives much
lower scores. If your application was rated by the first judge, it would
have a much higher total score than if it was assigned to the second judge.
We have a way to address this problem. We make sure that no matter which
judges are assigned to you, your application will be treated fairly. To do
this, we utilize a mathematical technique relying on two measures of
distribution, the mean and the standard deviation.
The mean takes all the scores assigned by a judge, adds them up, and divides
them by the number of scores assigned, giving us an average score. So, if a
judge is lenient, he will have a much higher average score than a harsh
judge.
Formally, we denote the mean like this:
\[ \overline{x} = \frac{1}{n} \sum_{i=1}^{n} x_{i} \]
The standard deviation measures the “spread” of a judge’s scores. So, maybe
two judges both give the same mean (average) score, but one gives a lot of
zeros and fives, while the other gives a lot of ones and fours. It wouldn't
be fair to you if we didn’t consider this difference.
Formally, we denote the standard deviation like this:
\[ \sigma = \sqrt{\frac{\sum_{i=1}^{n} (X_{i}-\overline{X})^2}{n-1}} \]
So, to ensure that the judging process is fair, we rescale all the scores to
match the judging population. In order to do this, we measure the mean and
the standard deviation of all scores across all judges. Then, we change the
mean score and the standard deviation of each judge to match.
We rescale the standard deviation like this:
\[ x_{i} = \frac{x_{i}}{(\sigma_{judge}/\sigma)} \]
Then, we rescale mean like this:
\[ x_{i} = x_{i}-(\overline{x}_{judge}-\overline{x}) \]
Basically, we are finding the difference between both the distributions for a
single judge and those for all of the judges combined, then adjusting each
score so that no one is treated unfairly according to which judges they are
assigned. If we apply this rescaling process to the same two judges in the
example above, we can see the outcome of the final resolved scores; they
appear more similar, because they are now aligned with typical distributions
across the total judging population.