The regression equation Y = 3 + 2X has been calculated from 6 pairs of values, with X ranging from 1 to 10. The correlation coefficient is 0.8. It is estimated that Y = 43 when X = 20. Which of the following are true? (i) The estimate is not reliable because X is outside the range of the data (ii) The estimate is not reliable because the correlation is low (iii) The estimate is reliable (iv) The estimate is not reliable because the sample is small
A、(i) and (ii) only
B、(i) and (iii) only
C、(ii) and (iv) only
D、(i) and (iv) only
A、(i) and (ii) only
B、(i) and (iii) only
C、(ii) and (iv) only
D、(i) and (iv) only
【参考答案及解析】
When X _ 20, we don't know anything about the relationship between X and Y since the sample data only goes up to X _ 10. (i) is therefore true.Since a correlation coefficient of 0.8 would be regarded as strong (it is a high value) the estimate would be reliable. (ii) is therefore not true.
When X _ 20, we don't know anything about the relationship between X and Y since the sample data only goes up to X _ 10. (i) is therefore true.Since a correlation coefficient of 0.8 would be regarded as strong (it is a high value) the estimate would be reliable. (ii) is therefore not true.