Negative predictive power

Such considerations have led to development of the concept of predictive power, which is more directly useful in evaluating the results from a screening instrument. Positive predictive power is the probability that a child identified by the instrument as having the disorder or symptom actually does have it, and negative predictive power is the probability that a child identified as not having the disorder or symptom actually does not have it. In some ways, predictive power is the converse of specificity and sensitivity, but it usually also depends on the base rate. If sensitivity is 100% then the negative predictive power would be 100%. If specificity is 100%, then positive predictive power is 100%. But when sensitivity and specificity are less than 100% (the usual situation), the base rate enters into the calculation. With 90% sensitivity, 90% specificity, and a 5% base rate, there are 4.5% true positives, 85.5%... 

Fig. 4. Predictive power of multivariate PLS-DA and PC-LDA on a subset of the initial data set for positive and negative ion mode. Different lines are relative to models constructed with an increasing number of LVs. The horizontal dashed line indicates random selection.

If the power dissipated into the system is increased, although the collapse pressure, as predicted using bubble dynamics analysis [14], decreases with an increase in the intensity, the number of cavitation events also increases (increase is substantial as compared to the negative effect of decreasing collapse pressure) thereby increasing the overall cavitational activity and hence enhanced effects can be observed. Usually the increase in number of cavities generated seizes after a... 

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