Types of Variables, Conceptual and Operational Definition A variable is a concept – noun which stands for variation within a class or objects (Ariola, 2006; Catane, 2000). Variable refers to characteristic [condition or attributes] that has two or more equally exclusive values or properties (Sevilla and Others, 1988 as cited in Ardales, 1992). Ariola (2006) states that variables can be manipulated, selected, controlled and observed by the researcher or experimenter (p. 121). Therefore variables can “vary”; it is a tool in measuring the values and determination of quantity of datum for the conducted research. According to Calmorin et al. (2007) a variable is defined as a quantity susceptible of fluctuation or change in value or in magnitude under different conditions (p. 14). The term variable has the correspondent term variation, which means difference and relationship per se. In mathematics, variables are use for graphing, problem solving, statistical computations, algebraic expression, and various kinds of equations, different functions, relations and measurement to analyze and interpret certain data. It is the same with social research but those attributes apply and take different form, thus they can belong to different levels of measurement ("Variable and attribute," 2011). Variables operated or utilized as a tool of measurement is for throughput which leads to conclusion of the study.

Based on Ariola (2006) the variable classified into two such as: The quantitative and qualitative variables, the quantitative variables can be measured like age, molar mass, temperature and other fundamental and derived units in different bodies of all known studies while the qualitative variables cannot be measured or cannot be expressed numerically like gender, civil status, stress, study habits and some other related mass nouns (p. 121 -122). In correlational studies, generally, there are two major types of variables, the independent variable and dependent variable. Together with, there are three secondary types: moderator variable, control variable and intervening variable. Babbie (2010) defines independent variable as a variable with values that are not complex in an analysis but are taken as simply given. An independent variable is presumed to cause or determine a dependent variable while dependent variable is assumed to depend on (p. 18).Independent variable is stimulus variable or experimental variable which is manipulated, measured or selected by the researcher or experimenter to determine the relationship in observed phenomena. It is capable of effecting change in the dependent variable (Ariola, 2006, p. 122); while dependent variable is the consequence the response variable which is observed and measured to determine the effect of the independent variable. Therefore, logically, dependent variable is the presumed effect and the variable that predicted to. In mathematical categories, the independent and dependent variable can be represented as X and Y respectively. The dependent variable Y varies depends the independent variable X for example, speed Y dependent on the time X. In social research, the independent variable affects the dependent variable. For instance, the heredity X affects the behaviour of the individual Y; the informal groups X affect the productivity of the organization Y. Independent variable has a sub-type called moderator variable. Moderator variable moderates or changes the relationship between the independent variable and dependent variable (Ariola, 2006, p. 123). Catane (2000) states that independent variable and moderator variable both have expected presumed causes on the dependent variable but since moderator variable is only secondary independent variable it is expected that their impact is not as big as the primary independent variable (p. 19). For example, the dimness and brightness of light X affects the student’s performance Y inside the classroom but suspects that special attention Z to students motivates them to perform efficiently, thus special attention Z considered as moderator variable. The other one is control variable, this variable is manipulated by the researcher in the process of neutralizing or eliminating extraneous variables which are not relevant. Kerlinger identified the four ways to control extraneous variable (Kerlinger, 1972, as cited in Catane, 2000, p. 26): (1) to eliminate the variable as a variable (2) through randomization (3) building the variable right into the design as an independent variables and (4) matching subjects. The last secondary type of variable is intervening variable. Tuckman defines intervening variable (Tuckman, 1972 as cited in Catane, 2000, p. 24) as: a factor theoretically affects the observed phenomenon but cannot be seen, measured or manipulated; its effect must be inferred from the effects of the independent variables and moderator variables, the intervening variable is that factor that exist but cannot be manipulated by the researcher. It means that intervening variable is the interference or disruption of the observed phenomena which cannot controlled by the researcher. It bears influence on the effect of independent variable and the dependent variable (Ariola, 2006, p. 124) like the teaching influences and methods X to student’s performance Y. However, the school facilities and the experience of that teacher from teaching, such methods and attitude per se affect the effects of that whole teaching intervention itself. Moderator variable is a partial independent variable because it has presumed but suspicious cause, but if the moderator variable exists but irrelevant to the study, it is considered as a control variable. If a control variable exists but cannot be manipulated, it is considered as intervening variable. Those can therefore be stated as the presumed causes of dependent variables. Bailey’s definition of concepts (Bailey, 1994 as cited in Catane, 2000, p. 17) as mental images or perception that may be impossible to observe or may have referents that are readily observable. Concepts are pure ideas formed in individual’s mind and is being convert to verbal or non-verbal communication. It may be absorbed from other concepts and reorganize it or reconceptualise to form a new concept. A set of which and ideas are also called theory. It defines a variable in a way which it should be called a conceptual definition. Conceptual definition is the theoretical meaning of a term or variable. This type of definition is assumed to accept the theory or it depends on (Cline, n.d.). Furthermore, that uses operationalization process where after such; it would now be called as an operational definition. According to Best and Kahn’s work on the operational variable (Best et al., 1998 as cited in Catane 2000) “much more precise and unambiguous definitions of variables can be stated in operational form which stipulates the operation by which they can be observed and measured.” McGuigan identified the two function of operational definition of variable (McGuigan, 1987 as cited in Catane, 2000, p. 27) These functions are to clarify the phenomenon under investigation and to communicate with each other in an unambiguous manner.Operational definitions provide feasibility of carrying out research activities intended for the study (Catane, 2000, p. 27). The example below shows the difference between the two.
|Conceptual Definition |Operational Definition |
|Temperature: measurement of hotness and coldness of an object |The result of measurement of an object on a thermometer. |
|Entropy :measurement of system disorder in an organization |The result of measurement of system disorder on a survey. |

Bibliography
Reference from Books and Internet Sources
Ardales, V.B. (1992). Basic concepts and methods in research. Quezon City: Great Books Trading.
Ariola, M.M. (2006). Principles and methods of research (1st ed.). Manila: Rex Book Store, Inc.
Babbie, E.R. (2010). The practice of social research [12th ed.]. Retrieved from http://books.google.com/books?id=QySynvetGQIC&printsec=frontcover&dq
Calmorin, L.P., & Calmorin, M.A. (2007). Research methods and thesis writing (2nd ed.). Manila: Rex Book Store, Inc.
Catane, J.A. (2000). Conducting research: a practical application (Rev. ed.). Quezon City: JMC Press.
Cline, A. (n.d.). Theoretical definitions. Retrieved from http://atheism.about.com/od/logicalarguments/a/def_theoretical.htm
Variable and attribute (research), (2011) Wikipedia. Retrieved August 04, 2011, from http://en.wikipedia.org/wiki/Variable_ (research)