Linear Statistical Models

Sample Quiz #1

Consider the design

	a1	a2	a3	a4
b1	a	b	c	d
b2	e	f	g	h

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

  |----A-----|-B-|----A*B----|
   x1  x2  x3  x4  x5  x6  x7  x8  x9  x10
   
a   1   1   1   1   1   1   1

b  -1   1   1   1  -1   1   1

c   0  -2   1   1   0  -2   1

d   0   0  -3   1   0   0  -3

e   1   1   1  -1  -1  -1  -1

f  -1   1   1  -1   1  -1  -1

g   0  -2   1  -1   0   2  -1

h   0   0  -3  -1   0   0   3

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, when each cell has 10 observations

Stata commands:

regress y x1 x2 x3 x4 x5 x6 x7
test x1 x2 x3

or

            R2y.x1 x2 x3   / (    3    )
F = ______________________________________
         ( 1 - R2y.x1-x7 ) / (   72    )

Linear Statistical Models Course