The dependent and independent variables they are the two main variables of any experiment or investigation. The independent (VI) is the one that changes or is controlled to study its effects on the dependent variable (VD). The dependent is the variable that is investigated and measured.
They can then be seen as cause (independent variable) and effect (dependent variable). The independent is controlled by the experimenter, while the dependent changes in response to the independent. Let's give an example with the following graphic:
This would be the price evolution of an Italian restaurant's pizzas based on their size. The dependent variable (y) would be the price, while the independent variable (x) would be the size. As can be seen, the small pizza costs 9 Euros, the medium one 12 Euros and the family one 15 Euros. Therefore, as the size of the pizza increases, it becomes more expensive. That is, the price would be dependent on the size.
Other examples:
-Effects of fruit consumption on physical endurance. Fruit consumption (VI), physical endurance (DV).
-Effects of sugar consumption on weight. Sugar consumption (VI), weight (DV).
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The independent variable (VI) is the one that changes or is controlled to see its effects on the dependent variable (VD). For example, a study wants to measure the effects of height on weight. Height is VI and weight is DV.
The IV can stand on its own and is not affected by anything the experimenter does or by another variable within the same experiment; hence its name "independent".
It is the variable that can be systematically managed or manipulated by the experimenter, whose controlled changes have a direct effect on the dependent variable..
Speaking from the mathematical point of view, they are the input elements to the equation or study model and are represented on the abscissa (x) axis in a graph.
In other words, it is the supposed "cause" in the relationship being studied. Generally, a single independent variable is chosen to avoid that several factors at the same time have effects on the dependent variable.
If that happened, it would be difficult to identify and measure which of the modifications in the "independent" variables is causing changes in observed behavior..
The independent variable is also known as a controlled variable or predictive variable depending on the type of study.
The dependent variable (VD) is the one that is affected by the independent variable (VD). It's about the effect, what is measured. For example, a study wants to measure the influence of the amount of sun that plants receive on their height. The amount of sun is the VI, it is the cause. The height of the plant would be the DV, the effect that is measured.
The dependent variable is represented on the y-axis of a graph. The changes observed in this variable are meticulously recorded as a fundamental part of the results of the experiment..
Depending on the type of study, it can also be known as an experimental variable, a measurement variable or a response variable..
- A study focuses on knowing the effects of paracetamol in reducing fever in a patient with coronavirus. The number of grams of medicine consumed daily would be the independent variable (cause), while fever will be the dependent variable (effect).
- The statistics center of a football team wants to know the victory options that your club has based on the level of the grass of the field of play. The size of the turf will be the independent variable (cause) and the number of victories will be the dependent variable (effect).
- A probiotic dairy company wants to analyze the effects of anti-cholesterol yogurt on its customers based on their regular consumption. The amount of yogurt ingested each day will be the independent variable (cause), while cholesterol levels would define the dependent variable (effect).
- The director of a school wants to know if the practice of sport influences the grades obtained. The practice of sports would be the independent variable and the grades obtained the dependent variable.
- Measure the effects of positive comments from parents to children (VI) on children's self-esteem (DV).
- Investigate exposure to sunlight (VI) in the happiness levels of adults and the elderly.
The independent could be controlled with the exposure time (hours, days, weeks), and the dependent with a multiple scale where workers are asked at the end of the day simply how they feel.
- Investigate the effects of the use of social networks (VI) on the school grades of children and adolescents (DV).
- Investigate the influence of educational level (VI) on salary level (DV).
- Investigate how salt intake (VI) affects blood pressure.
An agricultural study wants to examine how fertilizer can influence avocado growth. To do this, specific amounts of fertilizer are applied to each tree to determine how much the amount of fertilizer matters..
The data obtained are:
- Per 4 mg of fertilizer, the avocados grew to 2 cm
- Per 6 mg of fertilizer, the avocados grew to 5 cm
- Per 9 mg of fertilizer, the avocados grew to 10 cm
- Per 12 mg of fertilizer, the avocados grew to 15 cm
Find out which is the dependent and independent variable and make a representative graph of how it would look.
In this case, the independent variable (the cause) would be the amount of fertilizers, while the dependent variable (the effect) would be the yield of the size of avocados. That is, the size of the avocado will depend on the amount of fertilizer applied.
In the study the objective is to discover how much the use of fertilizers (variable x) will affect the size of the avocados (variable y). From the data obtained from the experiment we can create the following graph.
Types of variables.
Research techniques.
Types of research.
Research variables.
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