Choosing a Method for Investigating a Scientific Question

Instructor: David Wood

David has taught Honors Physics, AP Physics, IB Physics and general science courses. He has a Masters in Education, and a Bachelors in Physics.

Scientists spend their lives investigating the world. But there are many ways a scientist can investigate a topic. Learn about the various methods scientists use to investigate topic, and how they choose a method by understanding their strengths and weaknesses.

Investigating a Scientific Question

There's a lot of unanswered questions we have about the world. The job of a scientist is to answer these questions. It's a pretty great job, because you can let your curiosity run wild and figure out things that nobody else has.

The job of a scientist is to answer questions about the universe

At the center of that process is a scientific investigation, which collects data to answer a question. However, not every scientific investigation is the same. Matching the right type of investigation to a certain question is one of the first steps that a scientist needs to take. So how do they do it?

The Main Types of Investigation

Your goal is to figure out how one variable affects another. There's usually only one thing that you change. Keeping all the others the same makes it easier to figure out if one variable really caused a change in another. There are different types of investigations: field studies, systematic observations, controlled experiments, models, and simulations. Whichever kind of investigation you use, a lot of the key principles are the same.

Let's look at each type of scientific investigation in more detail.

Field Study

A field study is where you investigate something in a real-world environment without affecting that environment directly. For example, in zoology, you might investigate animal behavior by watching animals in their natural habitat. This has a lot of advantages, the main one is that the results tend to be very realistic.

Animals might behave differently in captivity than they do in real life, so a field study is a good way to get accurate data. The downside is that you can't properly control variables - there will always be multiple factors affecting a particular situation, and figuring out what exactly causes something to happen can be difficult.

The lab isn
rabbit in cage

Systematic Observation

A systematic observation is a way of taking something that would otherwise be a field study - something in real life - and reducing other variables and biases. Bias can be reduced by having many people observe the same event. And the effect of other variables can be reduced by focusing on one particular variable and exerting some control of the situation.

People should be able to do your experiment again and confirm your findings. Systematic observations are done a lot in medicine, because we need to know whether our interventions have the result we're hoping for.

Controlled Experiment

A controlled experiment is where you study something in a lab where every variable can be controlled. The only thing that should change is the cause and effect that you're studying.

For example, how does the roughness of a surface affect how fast a car slows down? In your investigation the only things that should change are the roughness of the surface and the rate the car slows. Everything else: the type of car, the kind of tires, the amount of wind, etc. should remain the same.

This is useful in a situation where you really need to know cause and effect with certainty. However, sometimes it's not so good when you need to study a real life situation where things happen differently than in a lab. This is especially true for psychological and zoological research.

Models and Simulations

Models and simulations are related concepts, and are generally used together in scientific investigations. A model is a way of representing something complex in the real world in a more simple way. For example, you could create a physical model of a rocket ship in order to do some tests on it, or you could create a mathematical model of the laws of gravity to help explain how they work.

Once you have a model, you can use it to run a simulation, a sort of test that imitates a process. This is where the scientific investigation comes into it. If you know the rules and laws that govern a situation, you can change the variables and see what happens. For example, you could run a simulation to see how the rocket might fly to Mars, or how the moon's gravity might affect a comet's direction.

Car crash simulation
Car crash simulation

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