Forty-two stations show percent

true negative values of 100%, indicating that all estimated 90th percentile values of fecal coliform concentrations of these stations appear in the

true negative zone, representing no fecal-contaminated shellfish.

But on this reading, it is unclear what, exactly,

true negative causal statements express.

There were 73 true positive (TP) specimens and 25

true negative (TN) observations for a total of observations in the true quadrants.

Applying equation (10) to find the

true negative (TN).

Specificity is the proportion of

true negatives or those who would not die that were judged negative by the test.

(12) Alternatively and equivalently, one can ask how many false positives one can accept for every true positive, or how many false negatives one can accept for every

true negative. Sometimes this is an easier method to implement, but it is a detail that will not be discussed here.

Increases the number of true positive and

true negative test results

Specificity is sometimes described as the

true negative rate.

[2] Nonstandard abbreviations: SAMHSA, Substance Abuse and Mental Health Services Administration; OF, oral fluid; DUID, driving under the influence of drugs; THC, [[DELTA].sup.9]-tetrahydrocannabinol; 11-OH-THC, 11-hydroxy-THC; THCCOOH, 11-nor-9-carboxy-THC; LOQ, limit of quantification; IV, intravenous; GC-MS-MS, gas chromatography-tandem mass spectrometry; 2D, 2-dimensional; CBD, cannabidiol; CBN, cannabinol; LOD, limit of detection; [[DELTA].sup.8]-THC, [[DELTA].sup.8]-tetrahydrocannabinol; TP, true positive; FN, false negative; TN,

true negative; FP, unconfirmed positive.

High Confidence Medium/Low Confidence Total Call In-Grammar Out-Of-Grammar Positive True Positive a False Positive c a + c Negative False Negative b

True Negative d b + d Total a + b c + d To draw an ROC curve, only the true positive rate (TPR) and false positive rate (FPR) are needed.

[18F]fluorocholine combined in-line positron emission tomography-computerized tomography was true positive in 1, false-positive in 2, false-negative in 9 and

true negative in 8 patients.

The percentages of voters saying they are less likely to vote for a candidate because of one of their personal associations probably overstates the

true negative impact for the candidates, mainly because voters who might not seriously consider voting for a candidate in the first place (e.g., Democrats for McCain or Republicans for Obama) often respond that they are "less likely" to vote for that candidate.