<s>
In	O
the	O
design	O
of	O
experiments	O
and	O
analysis	B-General_Concept
of	I-General_Concept
variance	I-General_Concept
,	O
a	O
main	B-General_Concept
effect	I-General_Concept
is	O
the	O
effect	O
of	O
an	O
independent	O
variable	O
on	O
a	O
dependent	O
variable	O
averaged	O
across	O
the	O
levels	O
of	O
any	O
other	O
independent	O
variables	O
.	O
</s>
<s>
The	O
term	O
is	O
frequently	O
used	O
in	O
the	O
context	O
of	O
factorial	O
designs	O
and	O
regression	O
models	O
to	O
distinguish	O
main	B-General_Concept
effects	I-General_Concept
from	O
interaction	O
effects	O
.	O
</s>
<s>
Relative	O
to	O
a	O
factorial	O
design	O
,	O
under	O
an	O
analysis	B-General_Concept
of	I-General_Concept
variance	I-General_Concept
,	O
a	O
main	B-General_Concept
effect	I-General_Concept
test	O
will	O
test	O
the	O
hypotheses	O
expected	O
such	O
as	O
H0	O
,	O
the	O
null	O
hypothesis	O
.	O
</s>
<s>
Running	O
a	O
hypothesis	O
for	O
a	O
main	B-General_Concept
effect	I-General_Concept
will	O
test	O
whether	O
there	O
is	O
evidence	O
of	O
an	O
effect	O
of	O
different	O
treatments	O
.	O
</s>
<s>
However	O
,	O
a	O
main	B-General_Concept
effect	I-General_Concept
test	O
is	O
nonspecific	O
and	O
will	O
not	O
allow	O
for	O
a	O
localization	O
of	O
specific	O
mean	O
pairwise	O
comparisons	O
(	O
simple	O
effects	O
)	O
.	O
</s>
<s>
A	O
main	B-General_Concept
effect	I-General_Concept
test	O
will	O
merely	O
look	O
at	O
whether	O
overall	O
there	O
is	O
something	O
about	O
a	O
particular	O
factor	O
that	O
is	O
making	O
a	O
difference	O
.	O
</s>
<s>
Main	B-General_Concept
effects	I-General_Concept
are	O
essentially	O
the	O
overall	O
effect	O
of	O
a	O
factor	O
.	O
</s>
<s>
A	O
factor	O
averaged	O
over	O
all	O
other	O
levels	O
of	O
the	O
effects	O
of	O
other	O
factors	O
is	O
termed	O
as	O
main	B-General_Concept
effect	I-General_Concept
(	O
also	O
known	O
as	O
marginal	O
effect	O
)	O
.	O
</s>
<s>
The	O
contrast	O
of	O
a	O
factor	O
between	O
levels	O
over	O
all	O
levels	O
of	O
other	O
factors	O
is	O
the	O
main	B-General_Concept
effect	I-General_Concept
.	O
</s>
<s>
The	O
difference	O
between	O
the	O
marginal	O
means	O
of	O
all	O
the	O
levels	O
of	O
a	O
factor	O
is	O
the	O
main	B-General_Concept
effect	I-General_Concept
of	O
the	O
response	O
variable	O
on	O
that	O
factor	O
.	O
</s>
<s>
Main	B-General_Concept
effects	I-General_Concept
are	O
the	O
primary	O
independent	O
variables	O
or	O
factors	O
tested	O
in	O
the	O
experiment	O
.	O
</s>
<s>
Main	B-General_Concept
effect	I-General_Concept
is	O
the	O
specific	O
effect	O
of	O
a	O
factor	O
or	O
independent	O
variable	O
regardless	O
of	O
other	O
parameters	O
in	O
the	O
experiment	O
.	O
</s>
<s>
In	O
factorial	O
designs	O
,	O
thus	O
two	O
levels	O
each	O
of	O
factor	O
A	O
and	O
B	O
in	O
a	O
factorial	O
design	O
,	O
the	O
main	B-General_Concept
effects	I-General_Concept
of	O
two	O
factors	O
say	O
A	O
and	O
B	O
be	O
can	O
be	O
calculated	O
.	O
</s>
<s>
The	O
main	B-General_Concept
effect	I-General_Concept
for	O
factor	O
A	O
can	O
be	O
computed	O
with	O
2	O
degrees	O
of	O
freedom	O
.	O
</s>
<s>
The	O
expected	O
value	O
for	O
the	O
mean	O
of	O
the	O
responses	O
in	O
column	O
i	O
is	O
while	O
the	O
expected	O
value	O
for	O
the	O
mean	O
of	O
the	O
responses	O
in	O
row	O
j	O
is	O
where	O
i	O
corresponds	O
to	O
the	O
level	O
of	O
factor	O
in	O
factor	O
A	O
and	O
j	O
corresponds	O
to	O
the	O
level	O
of	O
factor	O
in	O
factor	O
B	O
.	O
and	O
are	O
main	B-General_Concept
effects	I-General_Concept
.	O
</s>
<s>
A	O
table	O
can	O
show	O
the	O
layout	O
of	O
this	O
particular	O
design	O
with	O
the	O
main	B-General_Concept
effects	I-General_Concept
(	O
where	O
is	O
the	O
observation	O
of	O
the	O
ith	O
level	O
of	O
factor	O
B	O
and	O
the	O
jth	O
level	O
of	O
factor	O
A	O
)	O
:	O
</s>
<s>
The	O
"	O
Main	B-General_Concept
Effect	I-General_Concept
"	O
of	O
X	O
(	O
spiciness	O
)	O
when	O
we	O
are	O
at	O
Y1	O
(	O
not	O
crunchy	O
)	O
is	O
given	O
as	O
:	O
</s>
<s>
Likewise	O
,	O
the	O
"	O
Main	B-General_Concept
Effect	I-General_Concept
"	O
of	O
X	O
at	O
Y2	O
(	O
crunchy	O
)	O
is	O
given	O
as	O
:	O
</s>
<s>
Likewise	O
,	O
for	O
Y	O
,	O
the	O
overall	O
main	B-General_Concept
effect	I-General_Concept
will	O
be	O
:	O
</s>
<s>
For	O
the	O
Chicken	O
tasting	O
experiment	O
,	O
we	O
would	O
have	O
the	O
resulting	O
main	B-General_Concept
effects	I-General_Concept
:	O
</s>
