Don't change the order of test results.

        if (size == 0) {

            return 0f;

        }

        Collections.sort(mResults);

        final ArrayList<Long> resultsCopy = new ArrayList<>(mResults);

        Collections.sort(resultsCopy);

        final int idx = size / 2;

        return size % 2 == 0

                ? (double) (mResults.get(idx) + mResults.get(idx - 1)) / 2

                : mResults.get(idx);

                ? (double) (resultsCopy.get(idx) + resultsCopy.get(idx - 1)) / 2

                : resultsCopy.get(idx);

    }

    private double standardDeviation() {