When all results for trisomies 21 and 18 were combined, the researchers found that the

false-positive rates for standard screening were 4.

False-Positive Rate by Preparation Type (N = 494) (a) Preparation Type Smears Papanicolaou Modified Giemsa Cytocentrifuged (N = 323) (N = 139) Specimen (N = 32)

False-positive rate, % 15.

Perhaps the most striking aspect of the second-tier test relates not only to its ability to reduce

false-positive rates derived from screening for the primary metabolite of a disorder but also to its capacity to expand the number of disorders by using the same screen for the same metabolite as a secondary metabolite for other diseases.

However, Carriquiry says that the 27 percent

false-positive rate is not informative.

The detection rate of Doppler ultrasound was slightly lower than that for saline infusion, whereas the

false-positive rate of Doppler is around five times higher.

Effectively, for PPV to support an expectation of a positive being more likely correct than not (PPV > 50%), the

false-positive rate, [alpha], must be less than double the likelihood of the hazard, P[H], a specification for a monitoring method that is challenging to provide for very low-frequency hazards.

Using the conventional 1:270 second-trimester cutoff for anticipated cases of aneuploidy, six of the seven cases screened positive, however, the price was an additional

false-positive rate of 10%.

Screening results for trisomy 18 carried a

false-positive rate of 8%.

In one study conducted during the second trimester of pregnancy, ITA alone detected 78% of the Down syndrome cases at a 5%

false-positive rate (6, 7).

She adds, however, that the test has a

false-positive rate of 4 percent, which means that 4 percent of patients who test positive do not in fact have the cancer.

7%, which was significant, but the

false-positive rate increased by 18%, which did not meet the prehypothesis that the

false-positive rate would not exceed 15%.