def middle(lst, size):
    """Return the middle fraction of a sorted list, removing outliers."""
    mid_lst = sorted(list(lst))
    l_mid_lst = len(mid_lst)
    num_el = int(size * l_mid_lst)
    start = (l_mid_lst - num_el) // 2
    end = start + num_el
    mid_lst = mid_lst[start:end]
    return mid_lst