Taking all of those variables is impractical but some of them can be taken as a control variable. We considered only three variables that can impact students' academic performance as a control variable in this current study.

It indicates an admissible control set; in this optimal problem, we assume a restriction on the control variable such as 0 [less than or equal to] [u.sub.i](t) [less than or equal to] 1, because vaccination of all the susceptible individuals at one time is impossible.

Regardless of the control variable constrains, the optimal control allocation can be denoted as

Growth in sales is also a control variable of this study, which is the ratio of total assets ending to total assets beginning.

Under the same system data, control variable limits and constraints, the results for Case 1 and Case 2 obtained using the hybrid GSA-SQP approach reported in this paper are compared to some other algorithms reported in the literature as shown in Table II.

The Irish finance minister, Michael Noonan, has said that he is ready for legislation that would provide power to the central bank to control variable mortgage interest rates.

It is also possible to test for equality of variances in the control variable amount equal to not less than 0/021 and 0/05, then the null hypothesis (assuming equal variances) is rejected.

The authors do not acknowledge the potential problem of inconsistent practices of ELL designation across the public and private sectors, and neither adjust that key control variable accordingly nor report what happens if it is omitted from the statistical model.

Intervention programs such as healthy life campaign and rehabilitation program are applied in the model as control variable which depends on time.