In this work, we investigate c-optimal design for polynomial regression model without intercept. Huang and Chen (1996) showed that the c-optimal design for the dth degree polynomial with intercept is still the optimal design for the no-intercept model for estimating certain individual coe cients over [−1, 1]. We found the c-optimal designs explicitly for estimating other individual coe cients over [−1, 1], which have not been obtained earlier. For the no-intercept model, it is shown that the support points are scale invariant over [−b, b]. Finally some special cases are discussed for estimating the coe cients of the 2nd degree polynomial without intercept by Elfving theorem over nonsymmetric interval [a, b].

Current status data are usually obtained with a failure time variable T which is diffcult observed but can be determined to lie below or above a random monitoring time or inspection time t. In this work we consider bivariate current status data ${t,delta_1,delta_2}$ and assume we have some prior information of the bivariate failure time variables T1 and T2. Our main goal is to find an optimal inspection time for testing the relationship between T1 and T2.