Q.How do experimental and control groups differ? Explain with the help of an example.

An experiment is a method used to establish a cause-effect relationship between two variables under carefully controlled conditions, and its logical structure typically rests on comparing an experimental group with a control group. The experimental group consists of participants who are actually exposed to the manipulation of the independent variable, the factor the researcher deliberately changes. The control group, by contrast, is a comparison group treated identically to the experimental group in every other respect, but which is NOT exposed to that manipulation; it functions as the baseline against which any change in the experimental group can be judged. Latane and Darley's classic 1970 smoke-reporting study illustrates this structure well: participants who waited alone in a room with no other people present formed the control group; participants who waited with two other genuinely naive participants formed one experimental group; and participants who waited with two confederates instructed beforehand to ignore the smoke formed a second experimental group. Every condition of the room itself was kept identical across all three groups, and participants were assigned to groups randomly, so that any difference found afterwards in how often participants reported the smoke could confidently be attributed to the one thing that actually differed between groups, the presence or absence, and behaviour, of other people, rather than to any pre-existing difference between the kinds of people placed in each group. The results showed a clear pattern: control-group participants (alone) reported the smoke most often, the experimental group with uninstructed strangers reported it somewhat less, and the experimental group with passive confederates reported it least of all …