The control group refers to a subset of randomly selected experimental subjects, in which individuals have no special treatment. The reason why control groups are needed is that without control groups, there is no way to determine whether such operations or other variables (or several joint variables) have played a role.
Extended data:
Correlation principle:
There is no clear definition of "experimental group" and "control group" in biology, just like "set" in mathematics, it is just a basic concept. You can understand it this way: the experimental group refers to the part of experimental inquiry, and the control group refers to the part of experimental comparison. Generally, it can be distinguished from the following two angles:
1, the results of the experimental group were not known before, and can only be known through experiments. The control group is known by themselves and has no experimental common sense.
2. The experimental group is complex and has many variables, so it must be studied by "control variable method". The control group is very simple, with almost no variables. The following are three common control situations
1) blank control: that is, no treatment is given to the control group, or some experimental factors are given to the control group, but they are not the experimental treatment factors studied; In order to verify the effect of thyroid hormone, the animals in the control group grew naturally without any treatment, and the experimental group was fed with thyroid hormone preparation or thyroid inhibitor to observe the effect of thyroid hormone.
2) Self-control: Both the experimental group and the control group were conducted on the same experimental object. For example, in the experiment of observing the separation and repair of plant cells, the normal onion epidermal cells in the control group and the cells separated and repaired in the experimental group are the same group of cells, which is a typical self-control experiment.
3) Cross-control: There is no separate control group, but several experiments are cross-controlled. For example, in the experiment of "Comparison of Catalytic Efficiency of Catalase and Fe3+", catalase and Fe3+ were used to catalyze the decomposition of hydrogen peroxide respectively, and compared with each other, so as to draw the conclusion that this enzyme has high efficiency.
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