what is the difference between a control and a variable
To understand the difference between a control and a variable, let's start by defining each term:
1. Control: In the context of scientific experiments, a control is a standard against which experimental observations are evaluated. It is a group or condition that remains unchanged or unmanipulated throughout the experiment. The purpose of a control is to provide a baseline against which the effects of the variables can be measured and compared.
2. Variable: A variable is a factor or condition that can change or be manipulated during an experiment. Variables are typically divided into two types:
a. Independent Variable: This is the variable that is deliberately changed by the researcher in order to observe its effect on the dependent variable. It is also known as the "manipulated variable" because the researcher has control over it.
b. Dependent Variable: This is the variable that is measured or observed to determine the effect of the independent variable. It is also known as the "responding variable" because it responds to changes in the independent variable.
Now, let's illustrate the difference between a control and a variable using an example:
Suppose a researcher is conducting an experiment to determine the effect of different amounts of fertilizer on plant growth. The independent variable in this experiment would be the different amounts of fertilizer applied to each group of plants. The dependent variable would be the height or growth rate of the plants as a result of the varying amounts of fertilizer.
To establish a control in this experiment, the researcher would have a separate group of plants that does not receive any fertilizer. This control group would serve as a baseline, allowing the researcher to compare the growth of plants that received different amounts of fertilizer with those that received none.
In summary, the key difference between a control and a variable is that a control remains unchanged or unmanipulated throughout the experiment, serving as a comparison standard, whereas a variable is deliberately changed or manipulated to observe its effect on the dependent variable.