I want to use a regression line to predict the Sales (Y) of ice cream cones at the Baskin-Robbins in Galveston on Saturdays in summer. The X variable I will use will be the High Temperature for the day. In this way I can see what portion of the sales are due to fluctuations in the temperature. Certainly sales will fluctuate for other reasons, like if there is some special event in town or if it rains a lot. So I collect data: Sales and High Temperature for each of the 8 Saturdays in the summer so far.
a. y(hat) +- t(sub6) (std error)
b. y(hat) +- t(sub7) (std error)
c. y(hat) +- t(sub8) (std error)
Answer: a. y(hat) +- t(sub6) (std error)
I want to predict the sales on Saturday August 16 and I want a CLI interval prediction. What formula? (The subscript in the following is the number of degrees of freedom.)
a. y(hat) +- t(sub6) (std error)
b. y(hat) +- t(sub7) (std error)
c. y(hat) +- t(sub8) (std error)
Answer: a. y(hat) +- t(sub6) (std error)