Question

We have two independent populations A and B, with means H1 and 42 and variances o and ož, respectively. Parameter of interest is difference 0 = Hi - M2. To estimate the difference 0, we use ê = X - Y, where X and Y are the sample means from the respective populations, based on samples of sizes ni, n2, respectively. Which of the following statements is true? A. E[@] = 0 and Var[@] = o/nı + o2/n2 B. E[@] +0 and Var[@] = 01/nı + ož/n2 C. Elê] = 0 and Var[@] = o/nı - oż/n2 D. E[@] + 0 and Var[@] = oi/ni - ož/n2 E. none of the preceding

Answer 1

answer is The A: option Explanation: the value of the Because, expected difference between two sample means of their means is the difference Hence, Elê J=0 Variance is given by, 5%,+ oz or/m2 Var [ ô 3= o Hence, option A. E CÔJ = 0 and Varlên) - a + 8 m2 is the correct option

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