A population contains 10 units, labelled U1, U2, U3,.......U10. The value of a character Y under study, for Ui is Yi(1<=i<=10). In order to estimate the population mean, Y*, a sample of size 4 is drawn in the following manner:
- A simple random sample of size 2 is drawn without replacement from the units U2,U3,......U9; 2)The sample drawn in the first step is augmented by the units U1 and U10. Based on the above sample in the second part, suggest an unbiased estimator of Y* and obtain its variance.
The most basic question I want to ask here is not about the unbiased estimator, but how is Y related to U1,.....? 'Character under study for Yi' what does the phrase indicate?