1) y(i) = a + b x(i) + e(i), i=1,2,...n, a is in bushels and b has no units. a i
ID: 1093819 • Letter: 1
Question
1)
y(i) = a + b x(i) + e(i), i=1,2,...n,
a is in bushels and b has no units.
a is in bushels and b is in pounds of fertilizer.
a is in bushels per acre and b is in bushels per pound of fertilizer.
a is in pounds of fertilizer and b is in bushels.
2) Say that you estimate the model y = a + b*x + e and find b to be 2.91 and a to be 75.77. You also know that the sample mean of x is 10.1. What is the sample mean of y?
a is in bushels and b has no units.
a is in bushels and b is in pounds of fertilizer.
a is in bushels per acre and b is in bushels per pound of fertilizer.
a is in pounds of fertilizer and b is in bushels.
2) Say that you estimate the model y = a + b*x + e and find b to be 2.91 and a to be 75.77. You also know that the sample mean of x is 10.1. What is the sample mean of y?
Explanation / Answer
Since every additive term in RHS has unit same sa LHS,
therefore after adding they will make unit same as left hand side.
Therefore unit of
a is bushels
b x(i) is bushels
e(i) is bushels
Now,
given x(i) is in pounds of fertilizer
Therefore, b is in bushels per pound of fertilizer so as to make multiplication of bx(i) as bushels.
2)
sample mean of y,
y = 75.77 + (2.91)(10.1) + 2.71 = 107.871
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