An independent variable is a variable that is changed in an experiment to produce a result. As the name suggests, experiments are designed such that an independent variable isn't influenced by the other variables in the experiment. The results of an experiment are known as dependent variables. An experiment predicts that changing independent variables will produce a resulting change to dependent variables. The following are illustrative examples of independent variables.
FertilizerChanging the amount of fertilizer given to plants as an independent variable. In this experiment, dependent variables might be plant height and weight. Control variables might include water, sunlight and soil.
MedicationGiving medication to one group and a placebo to another. Dependent variables in this experiment might be measures of health outcomes. This type of experiment may have a large number of extraneous variables such as the diet, age and gender of participants.
FormulationsFormulations such as the amount of an essential oil in a natural pesticide.
DietThe food intake of an individual. For example, a diet high in simple carbohydrates such as sugar. Such an experiment might be ethically questionable as it may harm the health of participants. As such, a suitable natural experiment may be found to investigate changes to sugar in diet as an independent variable.
EnvironmentEnvironmental factors such as air quality. This is another scenario that calls for a natural experiment such as a health survey that compares the health of people in the same city by air quality levels at their primary residence.
Education LevelThe highest level of education completed by individuals. For example, an insurance industry study that models the impact of education on accident rates.
Design changes to a safety helmet. Dependent variables may include the result of crash tests conducted on the helmet.
ColorA product development group conducts market research using product color as an independent variable. This may influence consumer perceptions and choice.Businesses often experiment with prices, price structures and types of discounts as independent variables.
Different patterns of choices. For example, a foot in the door approach to sales that starts by asking for something small before asking for something larger.The framing and composition of written, verbal and visual communications. For example, a nudge versus a call to action.
Independent Variables vs Dependent VariablesIndependent variables are the variables you change or observe in an experiment. This can be thought of as a test variable. Dependent variables are the results of an experiment that are predicted to change when you change the independent variables.
Independent Variables vs Extraneous VariablesExtraneous variables are undesirable variables that aren't of interest to your experiment but may influence results. Efforts are made to control extraneous variables to hold them constant or reduce their influence over the experiment. Uncontrolled extraneous variables can cause an experiment to be invalid.
This is the complete list of articles we have written about experiments.
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