Q5 Confusion

Q5 Confusion

by Nicholas Arger -

I just want to make sure I am understanding the question right:

You are trying to estimate the likelihood that a fetus of a first-time mother has Trisomy 21.  How would you expect the LR+ for the mother being over 35 years old to differ in San Francisco compared with Todd County, SD? 

When it states "the LR+" for the mother being over 35 years old - do you mean what is the LR of Trisomy 21 based on the dichotomous <35  vs. >35 age cutoff (i.e. the LR for if a mother is >35) or is this a question of if the child has Trisomy 21, what is the likelihood for the mother being over 35. It's this "for the mother being over 35" part that I am confused about.


Thanks


Re: Q5 Confusion

by Thomas Newman -

The question says, "You are trying to estimate the likelihood that a fetus of a first-time mother has Trisomy 21."  So that's the thing you don't know.  You do know the mother's age.  

Tom