Research Design: Dependent and Independent Variables

Variables in education research are anything that can have different values or vary across learners. Dependent variables are the outcome variables that you collect data about in research, like learning outcomes. They apply to all research designs: non-experimental and experimental. All measurements used to evaluate or understand learning or a learning environment, such as test scores or attitudes, are dependent variables. Pre-tests and post-tests are dependent variables.

Independent variables represent differences in groups that you think might impact the dependent variables. Independent variables can be fixed, meaning they are manipulated by the researcher, or random, meaning they are pre-determined. Fixed independent variables (e.g., instructional style) are used in experimental designs, and participants must be able to be assigned to one value of the fixed variable (e.g., class instruction is based on lecture or active learning). The researcher manipulates the fixed variable to explore its effect on the dependent variable(s). Random independent variables (e.g., gender or religion) are used in non-experimental designs. These variables are not manipulated, but they can still represent a difference between groups on dependent variable(s). Random variables also include manipulable variables that are not manipulated, like which section of a course a student is in. If you have both fixed and random variables, then you have a quasi-experimental design.

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Research Design: Non-Experimental and Experimental Designs

The type of research design that you need depends on the type of research question that you have. Descriptive and relational questions can be answered with non-experimental designs, and causal questions must be answered by experimental designs. Note: these design categories are independent from pre-test and post-test designs, so you can have a pre-post non-experimental design or a pre-post experimental design.

Non-Experimental Design (descriptive and relational questions)

In non-experimental designs, researchers are measuring phenomena as they exist in the world, and they are not systematically manipulating anything, meaning there is no intervention. Because no systematic manipulation occurs, these designs can answer only descriptive or relational questions. Interactions between researchers and the participants in the study should be limited to what is necessary for collecting data. To collect data, researchers might ask participants to fill out surveys or another type of measure. If direct interaction with participants is impossible or might invalidate the data by biasing participants, an observational approach might be appropriate. In observational research, researchers do not directly interact with participants, but they collect data by carefully observing participant behaviors. An example of observational research would be counting the number of contributions from each student in an in-class discussion.

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Research Design: Pre- and Post-Tests

When you collect data has important implications for the conclusions that you can draw from that data. In education research, we often try to measure a difference, such as what students learn or how their experiences or perceptions change. Because we often try to make conclusions about differences, it can be equally important to take measurements at the beginning and end of a study.

Pre-Post Design

To measure a difference, we need to measure the level at which students start, such as their prior knowledge, and the level at which students finish, such as after a course or intervention, to make claims about how they’ve changed. The type of design that measures before (pre-test) and after (post-test) an intervention is called a pre-post design. This design is good at measuring any change from before the research started to after, such as how students’ perceptions of computer science differ from the beginning to the end of a course.

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Research Design: Research Questions

Many research questions in education come from observing something unexpected in the classroom, reading about a new method of instruction, or learning about a new tool. For example, you might find that a student has a unique explanation for a concept and want to know if it would help other students. Or you might have read about a metacognitive strategy and want to know if using that strategy would improve learning outcomes in your class. Your research methods will depend heavily on what type of research question you have.

There are three main types of research questions: descriptive, relational, and causal. A good research question in education explicitly identifies

  • the group that you are studying, such as online students, and
  • the variables you intend to manipulate or measure, such as the instructional strategy or student experience.
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Research Design: Series Introduction

Education research aims to understand how people learn and the effects of learning environments, including sociocultural factors. The ultimate goal is typically to improve learning and enable learners to achieve their goals. How researchers build this understanding and achieve this goal is called research design, which is critical to the quality and validity of the knowledge produced. Research design includes several aspects:

  • Crafting research questions that are interesting and answerable
  • Selecting research methods that are appropriate and thorough
  • Identifying or designing measurements that provide reliable and valid data
  • Conducting appropriate analysis of data based on the type of data and the research questions

Because my Ph.D. is in a social science, psychology, about half of my graduate coursework was about research design. In the computer science education community, the most requested talk in my repertoire is about research design. This interest is likely due to many people in our field not having formal training in this critical aspect of education research. Instead, they learn these skills primarily through apprenticeship. This series is designed to help those learning research design through an apprenticeship model.

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Wellness: Recovery: Dopamine

Many people have heard that dopamine is responsible for feelings of reward, but that’s only part of a highly complex system. The dopamine system developed to motivate us to seek things that have a cost or risk to attain. Evolutionarily, this included hunting for food, getting water, or gathering information. Dopamine motivates us to do things that we wouldn’t do for fun but are essential to survival. Because it works to motivate us, it is responsible for feelings of agitation (e.g., craving) as well as reward.

Our dopamine system maintains a balance over time. When we are at a healthy base level of dopamine, we feel an agitation that makes us motivated and focused on pursuing goals. When we achieve a goal, we have a surge of dopamine. The bigger the achievement, the bigger the surge. But there is a downside. Whenever dopamine surges above baseline, it must balance by dropping below baseline. The bigger the surge, the bigger the drop. This dopamine balance is why people sometimes feel unmotivated and lost after achieving a big goal. Low levels of dopamine inhibit our ability to feel motivated and focused.

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Wellness: Recovery: Sleep – Disruptors and Making the Best of Bad Sleep

High-quality sleep might be the best thing you can do for your health, but you can’t always control how well you sleep. Disrupted sleep was actually one of my primary catalysts to pay attention to my health. During the pandemic, I lived next to a guy who would throw loud parties 3-4 times a week until 12-1am. Because of the moratorium on evictions, there was nothing anyone could do about it, so I lived in this environment for over a year. I learned that while sleep is important, it’s not so precious that you can’t make the best of bad sleep.

It’s somewhat common to get so caught up in optimizing sleep that people develop sleep anxiety. Sleep anxiety then causes stress, which contributes to poor sleep. Poor sleep contributes to higher sleep anxiety in a maladaptive cycle. While this post discusses some common disruptors of sleep that you should avoid, it also discusses strategies for dealing with bad sleep to avoid this cycle of sleep anxiety. Like most things, perfect shouldn’t be the enemy of good. Sleep quality is not binary. If you can’t reach some ideal, you can still benefit from taking steps that are accessible to you.

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Wellness: Recovery: Sleep – Routines

Getting your sleep right is perhaps the best thing you can do for your health, but it’s hard to get quality sleep. Not only does it take a long time, but it’s easily disrupted because we’re so vulnerable while sleeping. If we could’ve evolved away from sleeping, we would have. Instead, most adults require 7-9 hours of quality sleep to maximize their health, especially mental health like mood and focus. This post focuses on routines for quality sleep because sleep depends on the circadian rhythm and, thus, reliable patterns.

Rule 1: I wake up at the same time each day (within an hour).

Including weekends. If I’m being honest, this rule doesn’t require any discipline most days. The benefit of prioritizing sleep quality is that I now wake up feeling refreshed and alert at about the same time each day. Sometimes I’ll sleep in for about 30 minutes if I had a hard day, but then I’m itching to get up. If that sounds annoyingly awesome, it is. But it all falls apart without the other rules.

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Wellness: Recovery: Serotonin – Sunlight and Gratitude

Serotonin is a molecule that makes people feel satisfied with what they have. And it does much more than that. It interacts with many other systems throughout the body, which is highlighted by the fact that it acts as both a neurotransmitter (i.e., communicates locally in the synapses between nerve cells) and hormone (i.e., communicates distally by circulating in the blood). Its complex nature helps explain why habits that support its healthy functioning can have substantial downstream benefits.

Serotonin is primarily part of a reward system that includes dopamine and cortisol. I’m starting with serotonin because the healthy habits are easier to implement than for dopamine, which will be in later posts. Cortisol, while healthy in some cases, is an inhibitor for both serotonin and dopamine, so chronic stress can disrupt both systems. Stress will be discussed extensively in later posts, too.

To produce serotonin, the body needs tryptophan, an essential amino acid (meaning you have to get it from food). Most people get plenty of tryptophan if they get enough protein, but it is more abundant in meat and dairy than plant-based food. Oats are a good source in plant-based diets. In turn, serotonin is used to produce melatonin, which is important for healthy sleep.

Rule 1: I get at least 20 minutes of direct sunlight a day and avoid bright screens after dark.

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Wellness: Recovery: Nutrition – Protein

As a former vegan, protein is an area where I’ve made many changes. Like dietary fat, we have to get sufficient protein from our diet to optimize health, and quality matters. I no longer believe that I can reach my best health potential without consuming animal products. Thus, high-quality and ethically-sourced protein is where I spend the most on investing in my health. If cost or animal ethics are a concern for you, I’ll also discuss some alternatives.

Rule 1: I eat about 100 grams of protein each day for maintenance or 140 grams for growth (for my current body weight, 140lbs or 63.5kg).

Muscle is critical for health. It allows you to engage in everyday activities without strain or injury. It protects your joints and gives you stability. It regulates various hormones throughout your body. It helps the body clear toxins that accumulate through normal functioning. It is generally protective for all body systems, and many age-related declines stem from lost muscle mass. However, muscle is also an energy-hungry tissue, and your body is constantly monitoring whether you’re consuming enough to maintain it.

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