christophM/interpretable-ml-book

Colors of Hormonal Contraceptives feature from SHAP summary plot seem wrong.

FWijanto opened this issue · 0 comments

Hi,
in chapter 9.6.6 a SHAP summary plot for a random forest model trained on the cervical cancer dataset is given. However, from what I checked, and from a previous explanation on chapter 9.5.2, the use of a hormonal contraceptive is correlated positively with an increase in cervical cancer risk. If the Hormonal Contraceptive feature (a yes/no categorical feature) is encoded by a 1 for a yes and a 0 for a no, then high values (red-coloured) of this feature should be seen on the x-axis of the summary plot as having a positive SHAP value and not a negative one as shown currently. Is my interpretation of this issue erroneous or is there a mistake in the plot?

Thank you for reading.

shap-importance-extended