Questionnaire Design | Methods, Question Types & Examples

A questionnaire is a list of questions or items used to gather data from respondents about their attitudes, experiences, or opinions. Questionnaires can be used to collect quantitative and/or qualitative information.

Questionnaires are commonly used in market research as well as in the social and health sciences. For example, a company may ask for feedback about a recent customer service experience, or psychology researchers may investigate health risk perceptions using questionnaires.

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Correlation vs Causation | Differences, Designs & Examples

Correlation means there is a statistical association between variables. Causation means that a change in one variable causes a change in another variable.

In research, you might have come across the phrase ‘correlation doesn’t imply causation’. Correlation and causation are two related ideas, but understanding their differences will help you critically evaluate and interpret scientific research.

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What Is a Likert Scale? | Guide & Examples

A Likert scale is a rating scale used to measure opinions, attitudes, or behaviours.

It consists of a statement or a question, followed by a series of five or seven answer statements. Respondents choose the option that best corresponds with how they feel about the statement or question.

Because respondents are presented with a range of possible answers, Likert scales are great for capturing the level of agreement or their feelings regarding the topic in a more nuanced way. However, Likert scales are prone to response bias, where respondents either agree or disagree with all the statements due to fatigue or social desirability.

Likert scales are common in survey research, as well as in fields like marketing, psychology, or other social sciences.

Download Likert scale response options

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Operationalisation | A Guide with Examples, Pros & Cons

Operationalisation means turning abstract concepts into measurable observations. Although some concepts, like height or age, are easily measured, others, like spirituality or anxiety, are not.

Through operationalisation, you can systematically collect data on processes and phenomena that aren’t directly observable.

Example: Operationalisation
The concept of social anxiety can’t be directly measured, but it can be operationalised in many different ways. For example:

  • Self-rating scores on a social anxiety scale
  • Number of recent behavioural incidents of avoidance of crowded places
  • Intensity of physical anxiety symptoms in social situations

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Correlational Research | Guide, Design & Examples

A correlational research design investigates relationships between variables without the researcher controlling or manipulating any of them.

A correlation reflects the strength and/or direction of the relationship between two (or more) variables. The direction of a correlation can be either positive or negative.

Positive correlation Both variables change in the same direction As height increases, weight also increases
Negative correlation The variables change in opposite directions As coffee consumption increases, tiredness decreases
Zero correlation There is no relationship between the variables Coffee consumption is not correlated with height

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Data Collection Methods | Step-by-Step Guide & Examples

Data collection is a systematic process of gathering observations or measurements. Whether you are performing research for business, governmental, or academic purposes, data collection allows you to gain first-hand knowledge and original insights into your research problem.

While methods and aims may differ between fields, the overall process of data collection remains largely the same. Before you begin collecting data, you need to consider:

  • The aim of the research
  • The type of data that you will collect
  • The methods and procedures you will use to collect, store, and process the data

To collect high-quality data that is relevant to your purposes, follow these four steps.

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Explanatory vs Response Variables | Definitions & Examples

In research, you often investigate causal relationships between variables using experiments or observations. For example, you might test whether caffeine improves speed by providing participants with different doses of caffeine and then comparing their reaction times.

  • An explanatory variable is what you manipulate or observe changes in (e.g., caffeine dose).
  • A response variable is what changes as a result (e.g., reaction times).

The words ‘explanatory variable’ and ‘response variable’ are often interchangeable with other terms used in research.

Cause (what changes) Effect (what’s measured)
Independent variable Dependent variable
Predictor variable Outcome/criterion variable
Explanatory variable Response variable

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Extraneous Variables | Examples, Types, Controls

In an experiment, an extraneous variable is any variable that you’re not investigating that can potentially affect the outcomes of your research study.

If left uncontrolled, extraneous variables can lead to inaccurate conclusions about the relationship between independent and dependent variables.

Research question Extraneous variables
Is memory capacity related to test performance?
  • Test-taking time of day
  • Test anxiety
  • Level of stress
Does sleep deprivation affect driving ability?
  • Road conditions
  • Years of driving experience
  • Noise
Does light exposure improve learning ability in mice?
  • Type of mouse
  • Genetic background
  • Learning environment

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What Are Control Variables | Definition & Examples

A control variable is anything that is held constant or limited in a research study. It’s a variable that is not of interest to the study’s aims but is controlled because it could influence the outcomes.

Variables may be controlled directly by holding them constant throughout a study (e.g., by controlling the room temperature in an experiment), or they may be controlled indirectly through methods like randomisation or statistical control (e.g., to account for participant characteristics like age in statistical tests).

Control variables

Examples of control variables
Research question Control variables
Does soil quality affect plant growth?
  • Temperature
  • Amount of light
  • Amount of water
Does caffeine improve memory recall?
  • Participant age
  • Noise in the environment
  • Type of memory test
Do people with a fear of spiders perceive spider images faster than other people?
  • Computer screen brightness
  • Room lighting
  • Visual stimuli sizes

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Mediator vs Moderator Variables | Differences & Examples

A mediating variable (or mediator) explains the process through which two variables are related, while a moderating variable (or moderator) affects the strength and direction of that relationship.

Including mediators and moderators in your research helps you go beyond studying a simple relationship between two variables for a fuller picture of the real world. These variables are important to consider when studying complex correlational or causal relationships between variables.

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