Repeated Trials: Definition & Purpose

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  • 0:00 What Are Repeated Trials?
  • 1:37 Recording,…
  • 4:17 Lesson Summary
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Lesson Transcript
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.

Repeated trials make the data you collect in experiments more reliable. Learn what repeated trials are, and find out how to record, organize, and analyze them.

What Are Repeated Trials?

Let's say that you want to become a famous scientist. You want to discover something new and amazing about the world. What do you do first? Well, you probably start by doing a science degree. But let's assume that you've already gotten that far. What would it take to achieve your goal? You could make some outlandish claims about how you think the world might work. Maybe you're such a genius that your claim is actually right. But it's unlikely that anyone will take you seriously. Why? Because the most important thing for a scientist is data. Science involves figuring out how the world works by collecting data using a systematic process called the scientific method.

Unfortunately, collecting data isn't always easy. Humans are notorious for being unreliable, and even when you do things perfectly there are certain random elements you can't do anything about. For example, if you measure the number of cars that pass down a road each hour, the number you get will be different depending on which day of the year you decide to do your experiments. Or if you use a stopwatch to measure how long it takes for the sun to rise, you have to take into account the fact that humans are not perfect at pressing the stopwatch at exactly the right time. It's unlikely that two numbers will ever be exactly the same.

The solution to these problems is to do repeated trials. Repeated trials are when you do a measurement multiple times - at least three, commonly five, but the more the better. When you measure something once, the chance that the number you get is accurate is much lower. But if you measure it several times, you can take an average of those numbers and get a result that is much closer to the truth.

Recording, Organization, and Analysis

Let's go through some of the details of how to do repeated trials. As an example, we'll imagine that our goal is to figure out what time of day is most popular for people to work out at the gym. You could sit outside the gym with a clipboard and note down how many people enter the gym at each hour of the day. But if you're going to get good data, you need to take repeated trials. Maybe you're collecting data on a Tuesday. To get repeated trials, you'd have to come back for at least three Tuesdays in a row and average your data. If there are a lot of people coming in and out because the gym is gigantic, you might even get more than one person to count and average those numbers, too. If you're interested in people's habits in general and not just at this particular gym, you might also want to collect data at different gyms and average those.

Each of those sets of measurements is an example of doing multiple trials. As part of your experiments, you might collect data on different days of the week, or at different times of the year. But those wouldn't count as extra trials, because they're simply ways of getting different or more detailed information.

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