We successfully made 3 SPRT classifications, all of which indicated inheritance of HapI by the fetus (Fig.
The classification of type a and type [beta] SNPs for the SPRT in RHDO analysis depends on the identities of the inherited paternal alleles, compared with those on an assigned maternal haplotype.
4] Nonstandard abbreviations: NIPD, noninvasive prenatal diagnosis; SNP, single- nucleotide polymorphism; RHDO, relative haplotype dosage; CVS, chorionic villus sampling; PE, paired-end; SOAP2, Short Oligonucleotide Alignment Program 2; Hapl, haplotype I; SPRT, sequential probability ratio test
Since both IRT and SPRT are the primary models in adaptive testing, and TOEFL is the benchmarking standard in our experiment, they are briefly introduced below.
Wald (1947) originally developed SPRT and Ferguson (1967) later adopted SPRT in education testing for the pass-or-fail decision.
In the standard SPRT execution, items were randomly selected, and the sequential probability ratio was calculated based on the item response.
Although SPRT does not involve complicated mathematical formulas, there are still two basic assumptions: A test item is randomly selected from the item bank and cannot be repeated, and it has local independence such as the one in the IRT.
First, Frick (1992) reported that IRT requires 200 to 1000 examinees to adjust the parameters, which consumes more time and human resources than SPRT in preparation.
We would like to emphasize that even though SPRT has been used inappropriately, such as in items varying widely in difficulty levels, and/or discriminating power is reaching a master or a non-master decision before a representative sample of items has been administrated to an examinee, the SPRT decision are highly accurate when prior error rates ([alpha] and [beta]) are kept at their minimum, as low as 0.
As a base, SPRT provides its simplicity in the item pool which consists only of items with equal levels of difficulty.
In creditable certified or license centers, it is even required that the SPRT item pool be rigorously verified against the three-parameter logistic model (PLM) IRT as suggested by Kalohn & Spray (1999).
The upper half of Figure 3 depicts a single SPRT process cycle, while the lower half represents the N-tier SPRT algorithm that determines how to repeat the single SPRT process cycle.