Example of an Experiment

ignored; within four minutes the room contained enough smoke to interfere with vision and breathing. Latane and Darley were primarily interested in knowing how frequently students simply got up and left the room to report the emergency. Most ( per cent) of the students who were waiting alone reported the smoke, but those reporting in groups were far less. Groups consisting of three naïve students reported it only per cent of the time.

When the students waited with two other confederates, who were instructed before hand by the researchers to do nothing, only per cent students reported smoke. which varies, that is, it takes on different values (or changes) and can be measured is a variable . An object by itself is not a variable. But its attributes are.

For example, the pen that you use for writing is NOT a variable. But there are varieties of pens available in different shapes, sizes, and colour. All of these are variables. The room in which you are sitting is NOT a variable but its size is as there are rooms of different sizes.

The height of the individuals ( ' to ') is another variable. Similarly, people of different races have different colours. Young people have started dyeing their hair in different colours. Thus, colour of hair becomes a variable.

Intelligence is a variable (there are people with varying levels of intelligence — high, moderate, low). The presence or absence of persons in the room is a variable as shown in the experiment in Box . . Thus, the variation can be in the quality or quantity of objects/events.

Variables are of many types. We will however focus on independent and dependent variables. Independent variable is that variable which is manipulated or altered or its strength varied by the researcher in the experiment. It is the effect of this change in the variable which the researcher wants to observe or note in the study.

In the experiment conducted by Latane and Darley (Box . ), the researchers wanted to examine the effect of the presence of other persons on reporting of the smoke. The independent variable was presence or absence of other persons in the room. The variables on which the effect of independent variable is observed is called dependent variable .

Dependent variable represents the phenomenon the researcher desires to explain. It is expected that change in the dependent variable will ensue from changes in the independent variable. The frequency of reporting of smoke in the above case was the dependent variable. Thus, the independent variable is the cause, and dependent variable the effect in any experimental situation.

One must remember that independent and dependent variables are interdependent. Neither of them can be defined without the other. Also, independent variable chosen by the researcher is not the only variable that influences the dependent variable. Any behavioural event contains many variables.

It also takes place within a context. Independent and dependent variables are chosen because of the researcher’s theoretical interest. However, there are many other relevant or extraneous variables that influence the dependent variable, but the researcher may not be interested in examining their effects. These extraneous variables need to be controlled in an experiment so that a researcher is able to pin-point the cause and effect relationship between independent and dependent variables.