Linear Statistical Models

Sample Quiz #3

Consider this randomized block design

	a1	a2	a3	a4
s1	a	d	g	j
s2	b	e	h	k
s3	c	f	i	l

1. Use orthogonal coding to code this design. Indicate which columns are for which effects. Hint: More columns are provided than are needed.

  |--  A  --|-- S --|
   x1  x2  x3  x4  x5  x6  x7  x8  x9  x10
a  1   1   1   1   1
b  1   1   1  -1   1
c  1   1   1   0  -2
d -1   1   1   1   1
e -1   1   1  -1   1
f -1   1   1   0  -2
g  0  -2   1   1   1
h  0  -2   1  -1   1
i  0  -2   1   0  -2
j  0   0  -3   1   1
k  0   0  -3  -1   1
l  0   0  -3   0  -2

2. Give the Stata commands beginning with regress that will test the A main effect or use R²'s to compute the F-ratio for A main effect.

Stata commands:  

regress y x1 x2 x3 x4 x5
test x1 x2 x3


or

         R2y.x1-x3       / (     3    )
F = ______________________________________
    (   1 - R2y.x1-x5  ) / ( 15 - 5 - 1 )

Linear Statistical Models Course