In a forensic study of the relation between time since death (hrs) and the thigh temperature in deer (F), a regression analysis of y = time since death on x = thigh temperature was performed. From their examination of the data the investigators felt that the assumptions of the linear regression model were satisfied. Summary quantities from this analysis yield:
a) Calculate the estimated standard deviation of a + bx* for x* = 80.
b) For what value x* is the estimated standard deviation of a + bx* smallest, and why?

Question

In a forensic study of the relation between time since death (hrs) and the thigh temperature in deer (F), a regression analysis of y = time since death on x = thigh temperature was performed. From their examination of the data the investigators felt that the assumptions of the linear regression model were satisfied. Summary quantities from this analysis yield:  ​ 
a) Calculate the estimated standard deviation of a + bx* for x* = 80. 
b) For what value x* is the estimated standard deviation of a + bx* smallest, and why?

Quizplus · Accepted Answer

The Answer of In a forensic study of the relation between time since death (hrs) and the thigh temperature in deer (F), a regression analysis of y = time since death on x = thigh temperature was performed. From their examination of the data the investigators felt that the assumptions of the linear regression model were satisfied. Summary quantities from this analysis yield:  ​ 
a) Calculate the estimated standard deviation of a + bx* for x* = 80. 
b) For what value x* is the estimated standard deviation of a + bx* smallest, and why?

In a Forensic Study of the Relation Between Time Since