UPDATE!!!!2025/2026|GUARANTEED
*2x2 Testing/Disease Table! Be able to draw. - ANSWER a= true positive
b= false positive
c= false negative
d= true negative
Using the letters- what are the equations for sensitivity and specificity -
ANSWER Sensitivity = TP/ (TP+FN) A/A+C
- % true pos, correctly ID'd by my test
Specificity = TN/(TN+FP) D/D+B
- % true neg, correctly ID'd by my test
Using the letters- what are the equations for positive predictive value and negative
predictive value - ANSWER PPV = a/ (a+b)
- of those my test says are pos, how many are truly pos?
NPV = d/(d+c)
- of those my test says are neg, how many are truly neg?
- ANSWER a= 24
b= 3
c=10
d= 63
1
, sensitivity = a/(a+c) = 24/34
- ANSWER a= 30
b= 5
c=4
d=101
specificity = d/(d+b) = 101/ 106
TP = 32
FP= 58
FN= 23
TN= 887 - ANSWER ppv = a/(a+b)
= 32 (32+58) = 32/90
TP = 47
FP= 112
FN= 22
TN= 819 - ANSWER npv= d (d+c)
- 819/ (819+22)= 819/841
- ANSWER Need to create your own population.
prevalence = TP
so if we choose 1000, then 100/1000 have HW and 900 are disease free.
96% sensitivity= will call 96/100 TP and 4 will be FN.
98% specificity= will call 882/900 TN and 18/900 are FP.
2
*2x2 Testing/Disease Table! Be able to draw. - ANSWER a= true positive
b= false positive
c= false negative
d= true negative
Using the letters- what are the equations for sensitivity and specificity -
ANSWER Sensitivity = TP/ (TP+FN) A/A+C
- % true pos, correctly ID'd by my test
Specificity = TN/(TN+FP) D/D+B
- % true neg, correctly ID'd by my test
Using the letters- what are the equations for positive predictive value and negative
predictive value - ANSWER PPV = a/ (a+b)
- of those my test says are pos, how many are truly pos?
NPV = d/(d+c)
- of those my test says are neg, how many are truly neg?
- ANSWER a= 24
b= 3
c=10
d= 63
1
, sensitivity = a/(a+c) = 24/34
- ANSWER a= 30
b= 5
c=4
d=101
specificity = d/(d+b) = 101/ 106
TP = 32
FP= 58
FN= 23
TN= 887 - ANSWER ppv = a/(a+b)
= 32 (32+58) = 32/90
TP = 47
FP= 112
FN= 22
TN= 819 - ANSWER npv= d (d+c)
- 819/ (819+22)= 819/841
- ANSWER Need to create your own population.
prevalence = TP
so if we choose 1000, then 100/1000 have HW and 900 are disease free.
96% sensitivity= will call 96/100 TP and 4 will be FN.
98% specificity= will call 882/900 TN and 18/900 are FP.
2
