The estimation results show that the proposed model well fits the real observations and performs better than the traditional Goel-Okumoto model and the Yamada delayed S-shaped model.
3] = 0, the original Goel-Okumoto model can be realized ; that is,
They correspond to our proposed model, the Goel-Okumoto model, the No-k model, the Only-G1 model, and the Yamada delayed S-shaped, respectively.
By comparing with the Goel-Okumoto model, the Yamada delayed S-shaped model, the No-k model, and the Only-G1 model, [R.
It is also much higher than those in the Goel-Okumoto model, the Yamada delayed S-shaped model, the No-k model, and the Only-G1 model.
The first case corresponds to the No-k model (14), the second case corresponds to the Only-G1 model (15), and the third case is just the Goel-Okumoto model (13).
As an example, we compare the Goel-Okumoto model and our proposed model when the type-I reliability definition is adopted and a is set as 95%.
Alternatively, when the type-II reliability definition is adopted, the Goel-Okumoto model predicts the best release time as 132.
Moreover, our proposed model recommends an earlier release time and a reduced cost compared with the Goel-Okumoto model and the Yamada delayed S-shaped model.
Solid line: our proposed mode; dot line: the Only-G1 model; dash-dot line: the Nok model; dash line: the Goel-Okumoto model.