UW Question # 1233

[natureboy]

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can anyone please explain how the 2x2 table was derived? I don't know where those numbers are coming from...I'm having a hard time wrapping my head around such what seems to be a somewhat simple concept, considering 50% answered it correctly.

 

[amestramgram]

Gold Standard Test
+ -
Your Test + (correct) (type 1 error)
Your Test - (type 2 error) (correct)

this sort of table helps you to see how well your test compares to the gold standard test for the condition in question. From this table, sensitivity, specificity, negative/positive predictive value can be derived.

 

[MediumDef]

can anyone please explain how the 2x2 table was derived? I don't know where those numbers are coming from...I'm having a hard time wrapping my head around such what seems to be a somewhat simple concept, considering 50% answered it correctly.

Make a 2x2 table and try to figure out what the boxes should be based on the sensitivity and specificity they give you and the formulas for specificity and sensitivity

e.g.

If sensitivity is 90% and is equal to TP/(TP+FN) and you test 100 people that have the disease than the number of TP is 90 and FN is 10.

Hope this helps enough to let you work through it on your own

 

[MLDstrctn]

Quick question about this problem...

Actually nm.