TABLE 4.

Illustration of the Association Between the Four Indices of Prediction Accuracy, Using Grade K or 1 Data and Grade 2 and 3 MLD Status as the Gold Standard for Presence of MLD

	Test Results = Positive (MLD)	Test Results = Negative (Not MLD)
Part 1: Definitions of Accuracy Indices
MLD	True positive	False negative	Sensitivity: P(test+|MLD+)
Not MLD	False positive	True negative	Specificity: P(test−|MLD−)
	Positive predictive value P(MLD+| test+)*	Negative predictive value P(MLD−| test−)
MLD Status at Grade 3	Test Positive (MLD)	Test Negative (Not MLD)
Part 2: Accuracy Based on Kindergarten Predictor Variables
MLD	26	15	Sensitivity: 0.63
Not MLD	61	104	Specificity: = 0.63
	Positive predictive value = 0.30	Negative predictive value = 0.87
MLD Status at Grade 3	Test Positive (MLD)	Test Negative (Not MLD)	Based on First Grade Data
Part 3: Accuracy Based on First-Grade Predictor Variables
MLD	12	29	Sensitivity: 0.29
Not MLD	11	159	Specificity: 0.94
	Positive predictive value = 0.52	Negative predictive value = 0.85

^*P(MLD+|test+) refers to the probability that a child is truly positive for MLD given that the test result for MLD is positive.