<s>
In	O
statistics	O
,	O
Hartley	B-General_Concept
's	I-General_Concept
test	I-General_Concept
,	O
also	O
known	O
as	O
the	O
Fmax	O
test	O
or	O
Hartley	O
's	O
Fmax	O
,	O
is	O
used	O
in	O
the	O
analysis	B-General_Concept
of	I-General_Concept
variance	I-General_Concept
to	O
verify	O
that	O
different	O
groups	O
have	O
a	O
similar	O
variance	O
,	O
an	O
assumption	O
needed	O
for	O
other	O
statistical	O
tests	O
.	O
</s>
<s>
The	O
resulting	O
ratio	O
,	O
Fmax	O
,	O
is	O
then	O
compared	O
to	O
a	O
critical	O
value	O
from	O
a	O
table	O
of	O
the	O
sampling	B-General_Concept
distribution	I-General_Concept
of	O
Fmax	O
.	O
</s>
<s>
Hartley	B-General_Concept
's	I-General_Concept
test	I-General_Concept
assumes	O
that	O
data	O
for	O
each	O
group	O
are	O
normally	O
distributed	O
,	O
and	O
that	O
each	O
group	O
has	O
an	O
equal	O
number	O
of	O
members	O
.	O
</s>
<s>
Alternatives	O
to	O
Hartley	B-General_Concept
's	I-General_Concept
test	I-General_Concept
that	O
are	O
robust	O
to	O
violations	O
of	O
normality	O
are	O
Brien	O
's	O
procedure	O
,	O
and	O
the	O
Brown	B-General_Concept
–	I-General_Concept
Forsythe	I-General_Concept
test	I-General_Concept
.	O
</s>
<s>
Hartley	B-General_Concept
's	I-General_Concept
test	I-General_Concept
is	O
related	O
to	O
Cochran	B-General_Concept
's	I-General_Concept
C	I-General_Concept
test	I-General_Concept
in	O
which	O
the	O
test	O
statistic	O
is	O
the	O
ratio	O
of	O
max(sj2 )	O
to	O
the	O
sum	O
of	O
all	O
the	O
group	O
variances	O
.	O
</s>
<s>
Hartley	B-General_Concept
's	I-General_Concept
test	I-General_Concept
and	O
these	O
similar	O
tests	O
,	O
which	O
are	O
easy	O
to	O
perform	O
but	O
are	O
sensitive	O
to	O
departures	O
from	O
normality	O
,	O
have	O
been	O
grouped	O
together	O
as	O
quick	O
tests	O
for	O
equal	O
variances	O
and	O
,	O
as	O
such	O
,	O
are	O
given	O
a	O
commentary	O
by	O
Hand	O
&	O
Nagaraja	O
(	O
2003	O
)	O
.	O
</s>
