I am writing a paper about the validity of a billing code in hospitalized children. I am a very novice R studio user. I need the confidence intervals for the sensitive and specificity and positive and negative predictive values but I can't figure out how to do it.
My data has 3 columns : ID, true value, billing value
Here is my code:
confusionMatrix(table(finalcodedataset$billing_value, finalcodedataset$true_value),
positive="1", boot=TRUE, boot_samples=4669, alpha=0.05)
here is the output:
Confusion Matrix and Statistics
0 1
0 4477 162
1 10 20
Accuracy : 0.9632
95% CI : (0.9574, 0.9684)
No Information Rate : 0.961
P-Value [Acc > NIR] : 0.238
Kappa : 0.1796
Mcnemar's Test P-Value : <2e-16
Sensitivity : 0.109890
Specificity : 0.997771
Pos Pred Value : 0.666667
Neg Pred Value : 0.965079
Prevalence : 0.038981
Detection Rate : 0.004284
Detection Prevalence : 0.006425
Balanced Accuracy : 0.553831
'Positive' Class : 1
You can use epiR package for this purpouse.
Example:
library(epiR)
data <- as.table(matrix(c(670,202,74,640), nrow = 2, byrow = TRUE))
rval <- epi.tests(data, conf.level = 0.95)
print(rval)
Outcome + Outcome - Total
Test + 670 202 872
Test - 74 640 714
Total 744 842 1586
Point estimates and 95 % CIs:
---------------------------------------------------------
Apparent prevalence 0.55 (0.52, 0.57)
True prevalence 0.47 (0.44, 0.49)
Sensitivity 0.90 (0.88, 0.92)
Specificity 0.76 (0.73, 0.79)
Positive predictive value 0.77 (0.74, 0.80)
Negative predictive value 0.90 (0.87, 0.92)
Positive likelihood ratio 3.75 (3.32, 4.24)
Negative likelihood ratio 0.13 (0.11, 0.16)
---------------------------------------------------------
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