What is Variable Research?
There is a saying that “no two individuals are alike even identical twins are different.” Even if twins have the same sex, they differ in their personality, attitude, character, skills, abilities and values. This stems from the fact that individuals are different.
A variable research is defined as a quantity susceptible of fluctuation or change in value or magnitude under different conditions. Numerical values or categories represent these quantities.
Types of Variable
There are five types of variables. These are independent variables, dependent variable, moderator variable, control variable, an intervening variable.
1. Independent variable. This is the stimulus variable which is chosen by the research to determine its relationship to an observed phenomenon. For instants, an investigator wants to determine the effect of chicken dung (independent variable) upon the yield (dependent variable) of carrots planted in pots. He plants carrots in five pots with different treatments such as 3%, 4%, 5%, 6%, and 7% of chicken dung as organic fertilizer. Chicken dung is the independent variable because it is the stimulus variable that is manipulated.
2. Dependent variable. This is the response variable which is observed and measures to determine the effect of the independent variable. It changes when the independent varies. For example, a research wishes to ascertain the effect of pellets upon the survival rate of prawn cultured in the fishpond. There are three rearing ponds with different treatments are 5%, 10% and 15% of pellets based on body weight of prawn. Survival rate is the dependent variable because it is the response variable and changes when the independent variable (pellets) varies.
In another example, a researcher wishes to determine the effect of academic rank professors, i.e., full professors, i.e., assistant professors, and observes their research performance. In this example, the dependent variable is research performance because it changes as a result of variation s in academic rank. If academic rank is high, what happens to research performance? If academic rank is low, what happens to research performance?
3. Moderator variable. This is a secondary or special type of independent variable chosen by the researcher to determine if it changes or modifies the relationships between the independent and dependent variables. For instance, if an investigator wishes to determine the effects of the independent variable A on the dependent variable B, but suspects that a third factor C changes or modifies the relationship between A and B, the C is considered as the moderator variable.
4. Control variable. This is a variable that is controlled by the investigator in which the effects of independent variable A on dependent variable B. He may control Z (control variable) because he cannot do many variables simultaneously. In other words, he may eliminate or remove D to neutralize the effects. Control variable will guarantee that it will not have a moderating effect on the relationship between A and B.
5. Intervening variable. This is a variable which interferes with the independent and dependent variables, but its effects can either strengthen or weaken the independent and dependent variables. For instance, a researcher wishes to determine how A (independent variable) will effect B (dependent variable). It is possible that F (intervening variable) might have an effect on B.
Suppose an investigator wishes to study the effect of pellets (5%, 10%, and 15%) as feed upon the survival rate of prawn cultured in the fishpond. Pellets (feed) are the independent variable. But it is possible that oxygen, salinity, temperature, and pH as intervening variables might have an effect on survival rate of prawn.
Another example is when a researcher wants the effect of lantay and hanging methods on the yield of Eucheuma cultured in Estancia Bay, Iloilo, Philippines. Lantay and hanging methods are independent variables and yield is the dependent variable. But it is possible that wave, salinity, temperature, oxygen, and pH as intervening variables might have an effect on the yield of Eucheuma.
As a third example, an investigator wishes to determine the effect of academic rank on the research achievement of professors. Academic rank is the independent variable and research achievement is the dependent variable. But it is possible that age, gender, civil status, experiences, socioeconomic status, values, and attitudes as intervening variables might have an effect on research performance.