def get_goal_difference_coefficient(score_team_1, score_team_2):
    """Get goal difference coefficient corresponding to a match score."""
    diff = abs(score_team_1 - score_team_2)
    if diff < 2:
        return 1
    elif diff == 2:
        return 1.5
    elif diff == 3:
        return 1.75
    else:
        return 1.75 + (diff - 3) / 8