Final exam question 1b

Final exam question 1b

by Thomas Newman -

Q: I am hoping you can clarify a question for me on the final.  I just want to make sure that my thinking is right. 

For question 1 part b it says to refer to the table and to look only at the first line.  Well this line is for a homescore of <10, whereas it is stated that a score > or = 10 is "positive".  So the labeling "true positive" for a score of <10, does this mean that this is a true positive for being negative in disease?  I am trying to fill out my 2x2 and dont want to get it backwards.  I just want to make sure I understand what it is asking of me.

 

Answer:  No, true positive means positive in disease.  Their labeling is confusing! Pretend the label that says <10 says >= 10 and it should make more sense. 

Re: Final exam question 1b

by Kimberly Rush -

Thank you.  And then my next thought is in table 4 it seems that this test could be dichotomous because there is only 2 results, >=10 and >=15.  And anything >10 is positive.  However, then in table 3, we are given multilevel scores.  For part c1, I am going to use an interval liklihood ratio because according to table 3 this test has multilevels.  However, anything over 10 is positive, so there are really only 2 results for the test, <10 negative or >10 positive.  I want to know what is intended with this question so I can determine the appropriate liklihood ratio to utilize.  Thank you.  

Re: Final exam question 1b

by Thomas Newman -

From your question it sounds like you can tell that the test is not dichotomous, because it has many different results: <10, 10 to < 15. > = 15 are three different results you mention.  (In fact, I think it's continuous.)  As to whether to calculate an interval likelihood ratio, I think lectures and text provided lots of guidance on  that question.

Tom