12.3.2 Reading
1. Difficult -
I find the law of total probability, the equation difficult to "attach" with the problem. I see intuitively how that works (the whole multiplying the two probabilities and then adding them up), but I'm not really getting the P(A) = the sum of P(ABi) P(Bi) as i=1 goes to n.
2. Reflective -
So, if I am understanding the tree diagrams correctly... as you said the lines connecting outcomes/events are like "ands" and should be multiplied (e.g. 1/200 times 0.99) ... and because we are interested in a positive test result we need to ADD opposite branches... (that is add the 199/200 times 0.5)... as they are not connected by a branch. So not only do "Ors" work with separate trees as the examples you gave us but on the same tree, just different paths? The paths need to be added up right? It sort of makes sense and the paths are not directly connected with a "branch."
I find the law of total probability, the equation difficult to "attach" with the problem. I see intuitively how that works (the whole multiplying the two probabilities and then adding them up), but I'm not really getting the P(A) = the sum of P(ABi) P(Bi) as i=1 goes to n.
2. Reflective -
So, if I am understanding the tree diagrams correctly... as you said the lines connecting outcomes/events are like "ands" and should be multiplied (e.g. 1/200 times 0.99) ... and because we are interested in a positive test result we need to ADD opposite branches... (that is add the 199/200 times 0.5)... as they are not connected by a branch. So not only do "Ors" work with separate trees as the examples you gave us but on the same tree, just different paths? The paths need to be added up right? It sort of makes sense and the paths are not directly connected with a "branch."
posted by Tina Marcroft at 8:02 PM
0 Comments:
Post a Comment
<< Home