Statistical Design of Experiments
Statistical Design of Experiments
Statistical Design of Experiments
Statistical Design of Experiments
Degrees of Freedom
Degrees of Freedom
Consider SS
Consider SS
A
A
Recall SS
Recall SS
A
A
is based on deviations
is based on deviations
y
y
y
y
i
i
A
A
Factor A has ‘a’ levels.
Factor A has ‘a’ levels.
There is only 1 overall
There is only 1 overall
mean
mean
Are comparing ‘a’ means to 1 of these until the last is
Are comparing ‘a’ means to 1 of these until the last is
one overall mean.
one overall mean.
Can vary a-1 of these until the last is
Can vary a-1 of these until the last is
pre -
pre -
determined from the rest.
determined from the rest.
Therefore, degrees freedom for
Therefore, degrees freedom for
Factor A is a-1.
Factor A is a-1.
How about SS
How about SS
E
E
?
?
n -
n -
a
a
How about SS
How about SS
total
total
?
?
n -
n -
1
1
 |
 |
 |