The prediction equation for predicting y (pain indicator) from X (drug dosage) is y = 2.5X + 18. What is the observation mean for Y if uX = 40 and óx square = 81?

To find the observation mean for Y, we need to use the given information about X and the prediction equation.

Given:
uX = 40 (mean of X)
óx^2 = 81 (variance of X)

The prediction equation is:
y = 2.5X + 18

To find the observation mean for Y, we substitute the given value of uX into the equation for X:

y = 2.5(40) + 18

Now we can calculate the value of y:

y = 100 + 18
y = 118

Therefore, the observation mean for Y is 118.