How Do You Know if Two Samples Are Independent or Dependent
Independent vs. Dependent Variables | Definition & Examples
In enquiry, variables are whatsoever characteristics that tin can have on unlike values, such every bit height, age, temperature, or test scores.
Researchers often dispense or measure out independent and dependent variables in studies to test cause-and-effect relationships.
- The independent variable is the cause. Its value is independent of other variables in your report.
- The dependent variable is the effect. Its value depends on changes in the independent variable.
Your independent variable is the temperature of the room. You vary the room temperature by making it cooler for half the participants, and warmer for the other half.
Your dependent variable is math examination scores. You measure the math skills of all participants using a standardized test and bank check whether they differ based on room temperature.
What is an independent variable?
An contained variable is the variable you manipulate or vary in an experimental study to explore its effects. It'due south called "independent" considering information technology's not influenced by any other variables in the study.
Independent variables are also called:
- Explanatory variables (they explain an consequence or event)
- Predictor variables (they tin be used to predict the value of a dependent variable)
- Correct-hand-side variables (they announced on the correct-hand side of a regression equation).
These terms are peculiarly used in statistics, where yous gauge the extent to which an independent variable alter tin explain or predict changes in the dependent variable.
Types of independent variables
There are two main types of independent variables.
- Experimental independent variables tin can be directly manipulated by researchers.
- Subject variables cannot be manipulated by researchers, but they can be used to group research subjects categorically.
Experimental variables
In experiments, you manipulate independent variables directly to see how they bear on your dependent variable. The independent variable is commonly applied at different levels to see how the outcomes differ.
Y'all can apply but two levels in order to notice out if an independent variable has an effect at all.
Yous can also apply multiple levels to find out how the independent variable affects the dependent variable.
You have three independent variable levels, and each group gets a dissimilar level of treatment.
Yous randomly assign your patients to ane of the three groups:
- A depression-dose experimental group
- A high-dose experimental group
- A placebo grouping
A true experiment requires you to randomly assign dissimilar levels of an independent variable to your participants.
Random assignment helps you control participant characteristics, so that they don't bear on your experimental results. This helps you to have confidence that your dependent variable results come solely from the contained variable manipulation.
Subject variables
Discipline variables are characteristics that vary across participants, and they can't exist manipulated by researchers. For example, gender identity, ethnicity, race, income, and education are all important subject variables that social researchers care for equally independent variables.
Information technology'southward non possible to randomly assign these to participants, since these are characteristics of already existing groups. Instead, you can create a research design where you compare the outcomes of groups of participants with characteristics. This is a quasi-experimental pattern because there'south no random assignment.
Your independent variable is a subject field variable, namely the gender identity of the participants. You have three groups: men, women and other.
Your dependent variable is the brain action response to hearing infant cries. You record brain activeness with fMRI scans when participants hear infant cries without their awareness.
After collecting information, you check for statistically pregnant differences between the groups. Yous find some and conclude that gender identity influences encephalon responses to baby cries.
What is a dependent variable?
A dependent variable is the variable that changes every bit a issue of the independent variable manipulation. It'due south the outcome y'all're interested in measuring, and it "depends" on your independent variable.
In statistics, dependent variables are also called:
- Response variables (they answer to a alter in another variable)
- Consequence variables (they represent the result you want to measure out)
- Left-hand-side variables (they appear on the left-hand side of a regression equation)
The dependent variable is what you lot record after y'all've manipulated the independent variable. You use this measurement data to check whether and to what extent your contained variable influences the dependent variable by conducting statistical analyses.
Based on your findings, you tin guess the caste to which your independent variable variation drives changes in your dependent variable. You tin also predict how much your dependent variable volition modify as a effect of variation in the independent variable.
Identifying independent vs. dependent variables
Distinguishing between independent and dependent variables can be tricky when designing a complex study or reading an academic paper.
A dependent variable from ane study tin can be the independent variable in another study, so it's important to pay attention to inquiry pattern.
Here are some tips for identifying each variable type.
Recognizing contained variables
Use this list of questions to check whether you're dealing with an contained variable:
- Is the variable manipulated, controlled, or used as a subject grouping method past the researcher?
- Does this variable come up before the other variable in fourth dimension?
- Is the researcher trying to understand whether or how this variable affects some other variable?
Recognizing dependent variables
Check whether you're dealing with a dependent variable:
- Is this variable measured as an upshot of the study?
- Is this variable dependent on another variable in the study?
- Does this variable become measured but after other variables are altered?
Independent and dependent variables in research
Independent and dependent variables are more often than not used in experimental and quasi-experimental enquiry.
Hither are some examples of research questions and respective independent and dependent variables.
| Inquiry question | Independent variable | Dependent variable(s) |
|---|---|---|
| Exercise tomatoes grow fastest under fluorescent, incandescent, or natural light? |
|
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| What is the effect of intermittent fasting on blood carbohydrate levels? |
|
|
| Is medical marijuana constructive for pain reduction in people with chronic hurting? |
|
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| To what extent does remote working increase job satisfaction? |
|
|
For experimental data, you analyze your results by generating descriptive statistics and visualizing your findings. And so, you lot select an appropriate statistical test to test your hypothesis.
The blazon of test is determined by:
- your variable types
- level of measurement
- number of independent variable levels.
You lot'll often utilize t tests or ANOVAs to analyze your information and answer your research questions.
Visualizing independent and dependent variables
In quantitative research, it'south skillful exercise to apply charts or graphs to visualize the results of studies. Generally, the contained variable goes on the ten-centrality (horizontal) and the dependent variable on the y-axis (vertical).
The blazon of visualization yous use depends on the variable types in your research questions:
- A bar nautical chart is ideal when y'all accept a categorical independent variable.
- A scatter plot or line graph is best when your independent and dependent variables are both quantitative.
To inspect your data, yous place your contained variable of treatment level on the x-axis and the dependent variable of blood force per unit area on the y-axis.
Yous plot bars for each treatment grouping earlier and after the treatment to show the difference in blood pressure level.
Based on your results, yous annotation that the placebo and low-dose groups evidence footling difference in blood pressure, while the high-dose grouping sees substantial improvements.
Often asked questions about independent and dependent variables
- What'southward the definition of an independent variable?
-
An contained variable is the variable yous manipulate, control, or vary in an experimental study to explore its effects. Information technology's called "independent" because information technology's not influenced by any other variables in the report.
Independent variables are as well called:
- Explanatory variables (they explain an event or outcome)
- Predictor variables (they can be used to predict the value of a dependent variable)
- Right-hand-side variables (they appear on the right-paw side of a regression equation).
- What'southward the definition of a dependent variable?
-
A dependent variable is what changes as a result of the independent variable manipulation in experiments. It's what you're interested in measuring, and information technology "depends" on your contained variable.
In statistics, dependent variables are also chosen:
- Response variables (they respond to a modify in another variable)
- Effect variables (they represent the effect you desire to measure)
- Left-mitt-side variables (they announced on the left-hand side of a regression equation)
- Tin can I include more than ane independent or dependent variable in a study?
-
Yes, but including more than i of either type requires multiple research questions.
For instance, if y'all are interested in the effect of a diet on health, you tin use multiple measures of wellness: claret sugar, claret pressure, weight, pulse, and many more. Each of these is its own dependent variable with its own research question.
You could also choose to look at the event of practice levels as well equally diet, or even the boosted consequence of the 2 combined. Each of these is a split independent variable.
To ensure the internal validity of an experiment, you should only alter one independent variable at a time.
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