Is it appropriate to use a regression line to predict yvalue

Is it appropriate to use a regression line to predict y-values that are not in (or close to) the range of x-values found in the ...

choose the correct answear below.

A. it is not appropriate because the correlation coefficient of the regression line may not be significant.

B. it is appropriate because the regression line will always be continous , so a y-value exists for every x-value on the axis.

c. it is a ppropriate because the regression line models a trend, not the actual points. so although the prediction of the y-value exact it will be precise.

d. it is not appropriate because the regression line models the trend of the given data, and it is not known if the trend continue range of those data.

Solution

The linear regression is only used to predict the values for the range of dependent variable over which it was modeled. For example if we modeled the dependent variable Y as a function of X using the simple linear regression model in (a,b) then the predictions can be done for the values of X lying in (a,b) only. This is because we don\'t know the nature of the function out of this interval. It may or may not be linear.

So, option (d) is correct.