Boxplot of welfare scores for housing systems by background (see also Table 2, n = 24 experts). Asterisks and circles indicate two types of outliers identified as standard practice in SPSS. Outliers are scores with values between 1.5 and 3 box lengths from the upper or lower edge of the box. The box length is the interquartile range (i.e. median 25% to 75% of values), while the horizontal line in the box indicates the median value. The two curved lines are connecting median values of ethologists (solid line) and veterinarians (dashed line) respectively.