Estimating the Population Mean in Stratified Random Sampling Using Combined Regression with the Presence of Outliers

In this research, the covariance estimates were used to estimate population mean in stratified random sampling and combined regression estimates. compared by employing robust variance-covariance matrices with traditional when estimating parameter, through two efficiency criteria (RE) squared error (MSE). We found that significantly improved quality of reducing effect outliers using (MCD, MVE) parameter. addition, results simulation study proved Minimum determinant (MCD) method is highly efficient at all sample sizes (n=35, 75, 150, 200, 500) then followed smallest ellipse volume Ellipsoid (MVE) handles dataset, where it has lower values (MSE).