C3_W3 Quiz Shapley value question

Course Q&A AI For Medicine AI For Medical Treatment
1

Based on https://www.coursera.org/learn/ai-for-medical-treatment/lecture/sPtIT/combining-importances, to calculate Shapley value, isn’t the feature we want to calculate needs to be the last entry?

Say, in Q3:
|Feature Set|Output|
|{}|0.5|
|{s_BP}|0.7|
|{d_BP}|0.6|
|{s_BP, d_BP}|0.65|

The only valid entry to calculate Shapley value is
|{s_BP}|0.7| - |{}|0.5| = 0.2

|{s_BP, d_BP}|0.65| - |{d_BP}|0.6| is not valid for calculating s_BP Shapley because d_BP is the last entry, not s_BP.

So the answer should be 0.2. Am I correct?
But the grader answer is 0.125 which assumes |{s_BP, d_BP}|0.65| - |{d_BP}|0.6| is a valid pair.

Is the problem, instruction, grader, or my understanding wrong?
Please help to clarify. Thank you

2

Hi @sunolbanjo,
Congratulations on making it so far; you are almost there!
You might want to check the video again. The order of the feature influences how you calculate.

1 Like
3

Hi, @S.Hassan ,
I reviewed the video again and now understand.
I’m able to complete 100% of the quiz. Thank you!

4

Great! I am glad to hear that you were able to fix it. :slight_smile: