Identification of variables to change and control

Variables in Investigations

Understanding the concept of a controlled experiment is essential for identifying variables.
A variable is a factor or condition that can change or be manipulated in a scientific investigation.
There are three types of variables to consider: dependent, independent, and controlled variables.

The independent variable is the one that you, the investigator, will change in the experiment.
The dependent variable is the one you measure or observe to see the effect of your change in the independent variable.
Controlled variables are quantities or factors that a scientist wants to remain constant, to ensure a fair test.

In an investigation into substances that inhibit microorganism growth, for example, the independent variable could be the type of substance used.
The dependent variable would be the growth of the microorganisms, which you would monitor or measure.
Other controlled variables might include temperature, light exposure, or the type of microorganism studied.

Controlled variables must remain constant to ensure that any changes in the dependent variable are likely due to the independent variable alone.
For instance, if you change the temperature in a growth inhibition experiment, it might affect the results, making it unclear whether it’s the substance or the temperature that’s inhibiting growth.
To make sure your experiment is valid, all aspects except for the independent variable must be kept constant.

Once the experiment is performed, you should evaluate the results to determine if your change in the independent variable has affected the dependent variable.
This process often involves statistical analysis, but the key aim is to ascertain whether the change was significant or if it could have been due to chance.
If your results do deviate, you may need to further investigate whether there were other variables at play that you did not control.