Weibull error

In the work described earlier, the applicability of the Weibull model was further tested by assessing the precision of estimation [expressed by the CV defined as the standard error of estimates divided by the estimated value] and the relative accuracy of estimation of the model parameters (based on the difference of the estimates from the actual value, divided by the actual value). Regarding the precision of estimates, for data with SD = 2 the maximum CV value for Wo, b, and c was 13%, 52%, and 16%, respectively, whereas the corresponding numbers for data with SD = 4 were 33%, 151%, and 34%, respectively. As expected, the precision of the estimates decreases as the SD of the data increases, with the poorest precision for the b estimates and the best for the Wo estimates. Additionally, the maximum CV values were associated with low c values (c = 0.5). 

Table 11 contains the pertinent parameter estimates and the residual error for each release model. From these results and from Figs 4, 5 and 6 it can be concluded that the release of diclofenac sodium is fitted by the Weibull distribution. P>1 (P being the shape parameter) is characteristic for a slower initial rate (diclofenac sodium is insoluble at pH 1.2) followed by an acceleration to the final plateau (sigmoid). In the direct compression optimization, after infinite time, the fraction released (F.rJ is estimated to be only 90% [13]. 

Table 3.4 Weibull Estimates of the Duration of Nonwork Spells in the Workers Compensation System The Direct Effects Model (standard error in parentheses) ...

Table 2. Error between the nonparametric and Weibull reliability for each subsystem.

Figure 3 shows that the Weibull fit matches well the nonparametric reUabUity curve, suggesting that a Weibull distribution represents reasonably well the TTC data. The goodness-of-fit of the Weibull distribution is simply measured in this work by the maximum and average errors over 15 years between the nonparametric reliability curve and the Weibull fit. Table 2 provides these results and indicates that the Weibull... 

The derivation of Equation (11.1) is given in Ref. [2]. The equation can be used to predict the reliability of a health care professional when his/her time to error follows any time-continuous probability distribution (e.g., exponential, normal, or Weibull). 

In the case of NaOH-treated fibers, irrespective of NaOH concentration, the possibility of occurrence of larger errors was felt when single fiber diameter was considered, while the scatter was low, when Weibull distribution was applied to each fiber treatment. 

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