<s>
Variable	B-General_Concept
rules	I-General_Concept
analysis	I-General_Concept
is	O
a	O
set	O
of	O
statistical	O
analysis	O
methods	O
in	O
linguistics	O
that	O
are	O
commonly	O
used	O
in	O
sociolinguistics	O
and	O
historical	O
linguistics	O
to	O
describe	O
patterns	O
of	O
variation	O
between	O
alternative	O
forms	O
in	O
language	O
use	O
.	O
</s>
<s>
It	O
is	O
also	O
sometimes	O
known	O
as	O
Varbrul	B-General_Concept
analysis	O
,	O
after	O
the	O
name	O
of	O
a	O
software	O
package	O
dedicated	O
to	O
carrying	O
out	O
the	O
relevant	O
statistical	O
computations	O
(	O
Varbrul	B-General_Concept
,	O
from	O
"	O
variable	O
rule	O
"	O
)	O
.	O
</s>
<s>
A	O
variable	B-General_Concept
rules	I-General_Concept
analysis	I-General_Concept
is	O
designed	O
to	O
provide	O
a	O
quantitative	O
model	O
of	O
a	O
situation	O
where	O
speakers	O
alternate	O
between	O
different	O
forms	O
that	O
have	O
the	O
same	O
meaning	O
and	O
stand	O
in	O
free	O
variation	O
,	O
but	O
in	O
such	O
a	O
way	O
that	O
the	O
probability	O
of	O
choice	O
of	O
either	O
the	O
one	O
or	O
the	O
other	O
form	O
is	O
conditioned	O
by	O
a	O
variety	O
of	O
context	O
factors	O
or	O
social	O
characteristics	O
.	O
</s>
<s>
A	O
variable	B-General_Concept
rules	I-General_Concept
analysis	I-General_Concept
computes	O
a	O
multivariate	O
statistical	O
model	O
,	O
on	O
the	O
basis	O
of	O
observed	O
token	O
counts	O
,	O
such	O
that	O
each	O
determining	O
factor	O
is	O
assigned	O
a	O
numerical	O
factor	O
weight	O
that	O
describes	O
how	O
it	O
influences	O
the	O
probabilities	O
of	O
choice	O
of	O
either	O
form	O
.	O
</s>
<s>
Although	O
the	O
necessary	O
computations	O
required	O
for	O
a	O
variable	B-General_Concept
rules	I-General_Concept
analysis	I-General_Concept
can	O
be	O
carried	O
out	O
with	O
the	O
help	O
of	O
mainstream	O
general-purpose	O
statistics	O
software	O
packages	O
such	O
as	O
SPSS	B-Algorithm
,	O
it	O
is	O
more	O
often	O
done	O
by	O
means	O
of	O
a	O
specialised	O
software	O
dedicated	O
to	O
the	O
needs	O
of	O
linguists	O
,	O
called	O
Varbrul	B-General_Concept
.	O
</s>
<s>
It	O
was	O
originally	O
written	O
by	O
David	O
Sankoff	O
and	O
currently	O
exists	O
in	O
freeware	B-License
implementations	O
for	O
Mac	B-Application
OS	I-Application
and	O
Microsoft	B-Application
Windows	I-Application
,	O
under	O
the	O
title	O
of	O
Goldvarb	O
X	O
.	O
</s>
<s>
There	O
are	O
also	O
versions	O
implemented	O
in	O
the	O
statistical	O
language	O
R	B-Language
and	O
therefore	O
available	O
on	O
most	O
platforms	O
.	O
</s>
<s>
These	O
include	O
R-Varb	O
and	O
Rbrul	O
.	O
</s>
