A VARIABLE is a measurable characteristic that varies. In science, the things that are changing in an experiment are called variables.
There are six common types of variables. The following are usually observed in an experiment.
DEPENDENT VARIABLES show the effect of manipulating or introducing the independent variables. For example, if the independent variable is the use
or non-use of a new language teaching procedure, then the dependent variable might be students' scores on a test of the content taught using that procedure. In other words,the variation in the dependent variable depends on the variation in the independent variable.
INDEPENDENT VARIABLES are those that the researcher has control over. This "control" may involve manipulating existing variables (e.g., modifying existing methods of instruction) or introducing new variables (e.g.,
adopting a totally new method for some sections of a class) in the research
setting. Whatever the case may be, the researcher expects that the
independent variable(s) will have some effect on (or relationship with) the
dependent variables.
INTERVENING VARIABLES refer to abstract processes that are not directly observable but that link the independent and dependent variables. Inlanguage learning and teaching, they are usually inside the subjects' heads,including various language learning processes which the researcher cannot observe. For example,if the use of a particular teaching technique is the independent variable and mastery of the objectives is the dependent variable, then the language learning processes used by the subjects are the intervening variables.
MODERATOR VARIABLES affect the relationship between the independent and dependent variables by modifying the effect of the intervening variable(s).Unlike extraneous variables, moderator variables are measured and taken into consideration. Typical moderator variables in TESL
and language acquisition research (when they are not the major focus of the study) include the sex, age, culture, or language proficiency of the subjects.
CONTROL VARIABLES. Since it is not possible to consider every variable in a single study, the variables that are not measured in a particular study must be held constant, neutralized/balanced, or eliminated, so they will
not have a biasing effect on the other variables. Variables that have been
controlled in this way are called control variables.
EXTRANEOUS VARIABLES are those factors in the research environment which may have an effect on the dependent variable(s) but which is not controlled. Extraneous variables are dangerous.They may damage a study's validity,making it impossible to know whether the effects were caused by the independent and moderator variables or some extraneous factor.If they cannot be controlled,extraneous variables must atleast be taken into consideration when interpreting results.
There are two types of data or should we say variables.As illustrated in
the figure above,these are categorical and numerical.Categorical variables are also known as qualitative variables while numerical variables are
oftentimes called continuous variables or quantitative variables. Whatever the name is, don’t get confused. They may differ in what they are made up of. Categorical variables are made of words while numerical variables are made of numbers.
There are two types of categorical variables. These are nominal and
ordinal variables.
A nominal variable is one of the 2 types of categorical variables and is
the simplest among all the measurement variables.
Examples of nominal variables:
a. gender
b. name
The responses to a nominal variable can be divided into two or more categories. For example, gender is a nominal variable that can take responses male/female, which are the categories the nominal variable is
divided into. Gender is considered as dichotomous variable.This variable is a nominal variable which have only two categories or levels.A nominal variable is qualitative, which means numbers are used here only to categorize or identify objects. For example,the number at the back of a player's jersey is used to identify the position he/she is playing.They can also take quantitative values.However,these quantitative values do not have numeric properties.That is, arithmetic operations cannot be performed on
them.
