Variation is a characteristic of
language: there is more than one way of
saying the same thing. Speakers may vary
pronunciation, word choice, or
morphology and syntax. But while the
diversity of variation is great, there
seem to be boundaries on variation –
speakers do not generally make drastic
alterations in sentence word order or
use novel sounds that are completely
foreign to the language being spoken.
Language variation does not equate with
language ungrammaticality, but speakers
are still sensitive to what is and is
not possible in their native tongue.
Language variation is a core concept in
sociolinguistics. Sociolinguists
investigate whether this linguistic
variation can be attributed to
differences in the social
characteristics of the speakers using
the language, but also investigate
whether elements of the surrounding
linguistic context promote or inhibit
the usage of certain structures.
Studies of language variation and its
correlation with sociological
categories, such as William Labov's 1963
paper "The social motivation of a sound
change," led to the foundation of
sociolinguistics as a subfield of
linguistics. Although contemporary
sociolinguistics includes other topics,
language variation and change remains an
important issue at the heart of the
field.
Sociolinguistic variables 
Studies in the field of sociolinguistics
typically take a sample population and
interview them, assessing the
realisation of certain sociolinguistic
variables. Labov specifies the ideal
sociolinguistic variable to
be high in frequency,
have a certain immunity from conscious
suppression,
be an integral part of larger
structures, and
be easily quantified on a linear scale.
Phonetic variables tend to meet these
criteria and are often used, as are
morphosyntactic variables,
morphophonological variables, and, more
rarely, lexical variables. Examples for
phonetic variables are: the frequency of
the glottal stop, the height or backness
of a vowel or the realisation of
word-endings. An example of a
morphosyntactic variable is the
frequency of negative concord. Two
well-known and frequently studied
morphophonological variables are T/D
deletion, the optional deletion of the
sound  or  at the end of a word, as in
"I kep' walking"; and the ING variable,
the optional pronunciation of -ing at
the end of a word as -in', as in "I kept
walkin'".
Analysis and methodology 
Analyzing sociolinguistic variation
often involves the use of statistical
programs to handle its multi-variable
nature. One essential part of the
methodology is to count up the number of
tokens of a particular variant and
compare it to the number of times the
variant could have occurred. This is
called the "Principle of Accountability"
in Tagliamonte. Comparing the tokens to
the total number of words in a corpus or
comparing one corpus to another leads to
erroneous results. This count of the
possible occurrences can be difficult at
times because some variants alternate
with zero.
Variation associated with age 
There are several different types of
age-based variation one may see within a
population. They are: vernacular of a
subgroup with membership typically
characterized by a specific age range,
age-graded variation, and indications of
linguistic change in progress.
One example of subgroup vernacular is
the speech of street youth. Just as
street youth dress differently from the
"norm", they also often have their own
"language". The reasons for this are the
following: To enhance their own cultural
identity To identify with each other, To
exclude others, and To invoke feelings
of fear or admiration from the outside
world. Strictly speaking, this is not
truly age-based, since it does not apply
to all individuals of that age bracket
within the community.
Age-graded variation is a stable
variation which varies within a
population based on age. That is,
speakers of a particular age will use a
specific linguistic form in successive
generations. This is relatively rare.
J.K. Chambers cites an example from
southern Ontario, Canada where the name
of the letter 'Z' varies. Most of the
English-speaking world pronounces it
'zed'; however, in the United States, it
is pronounced 'zee'. A linguistic survey
found that in 1979 two-thirds of the
12-year-olds in Toronto ended the
recitation of the alphabet with the
letter 'zee' where only 8% of the adults
did so. Then in 1991, a survey showed
only 39% of the 20- to 25-year-olds used
'zee'. In fact, the survey showed that
only 12% of those over 30 used the form
'zee'. This seems to be tied to an
American children's song frequently used
to teach the alphabet. In this song, the
rhyme scheme matches the letter Z with V
'vee', prompting the use of the American
pronunciation. As the individual grows
older, this marked form 'zee' is dropped
in favor of the standard form 'zed'.
People tend to use linguistic forms that
were prevalent when they reached
adulthood. So, in the case of linguistic
change in progress, one would expect to
see variation over a broader range of
ages. William Bright provides an example
taken from American English, where in
certain parts of the country there is an
ongoing merger of the vowel sounds in
such pairs of words as 'caught' and
'cot'. Examining the speech across
several generations of a single family,
one would find the grandparents'
generation would never or rarely merge
these two vowel sounds; their children's
generation may on occasion, particularly
in quick or informal speech; while their
grandchildren's generation would merge
these two vowels uniformly. This is the
basis of the apparent-time hypothesis
where age-based variation is taken as an
indication of linguistic change in
progress.
Variation associated with geography 
A commonly studied source of variation
is regional dialects. Dialectology
studies variations in language based
primarily on geographic distribution and
their associated features.
Sociolinguists concerned with
grammatical and phonological features
that correspond to regional areas are
often called dialectologists.
Variation associated with gender 
Men and women, on average, tend to use
slightly different language styles.
These differences tend to be
quantitative rather than qualitative.
That is, to say that women use a
particular speaking style more than men
do is akin to saying that men are taller
than women.
The initial identification of a women's
register was by Robin Lakoff in 1975,
who argued that the style of language
served to maintain women's role in
society. A later refinement of this
argument was that gender differences in
language reflected a power difference.
However, both these perspectives have
the language style of men as normative,
implying that women's style is inferior.
More recently, Deborah Tannen has
compared gender differences in language
as more similar to 'cultural'
differences. Comparing conversational
goals, she argued that men have a report
style, aiming to communicate factual
information, whereas women have a
rapport style, more concerned with
building and maintaining relationships.
Such differences are pervasive across
media, including face-to-face
conversation, written essays of primary
school children, email, and even toilet
graffiti.
Communication styles are always a
product of context, and as such, gender
differences tend to be most pronounced
in single-gender groups. One explanation
for this, is that people accommodate
their language towards the style of the
person they are interacting with. Thus,
in a mixed-gender group, gender
differences tend to be less pronounced.
A similarly important observation is
that this accommodation is usually
towards the language style, not the
gender of the person . That is, a polite
and empathic male will tend to be
accommodated to on the basis of their
being polite and empathic, rather than
their being male.
See also 
Dialect
Language change
Speech community
Variable rules analysis
Variety
Explanatory notes 
Citations 
Works consulted 
University of Pennsylvania. circa 2005.
Phonological atlas of North America, Map
1.
