The term experiment refers to any situation in which one thing is done along with something that is already happening. For example, if you were baking a cake, then testing its color, setting it aside and boiling water is an experiment because you are adding water while the cake is not.
In science, experiments are used to test whether or not two things are related. A lot of times these tests are practical, such as determining the best way to organize your room or what flavor of yogurt should be bought.
However, scientific experimentation can also look at much bigger questions. This could be investigating how air pollution affects the environment or studying why some people get sick more often than others.
The important part about experimenting in science is ensuring that the results you get are valid. Verifying the accuracy of your experiment will help prove your hypothesis!
Scientists use several methods to verify their findings including repeatability, replication, and controllable variables. In this article, we will go over each of these concepts and apply them to our research question.
If you would like to learn more about experimental design, check out our past lesson here: https://www.teachersbloomer.com/topic/experimental-design-scientific-research/
This article has been organized into three parts. Part 1 will talk about what makes an experiment have external validity, internal validity, and reliability.
They repeat the experiment
Another way to test whether or not your hypothesis was correct is to perform an independent experiment. This means doing the same experiment, but using different conditions or materials. If the new experiment confirms the original hypothesis, then you can trust that initial hypothesis!
Repeating an experiment isn’t always possible, however. In those cases, you have to be sure that there were no errors in the first experiment.
For example, if our hypothetical experiment consisted of testing whether chocolate tastes better when it is warm, we would need to make sure that we did not mix up the temperatures during the first test.
If this was done and the experimental results showed that chocolate tastes best when it is cold, then we cannot accept the theory that chocolate tastes good when it is hot. We will have to rethink our hypothesis.
They use control groups
In experimental research, one group is selected to perform a procedure or treatment on some participants while another group does not receive the intervention. This is called a controlled experiment because scientists can determine whether there are differences in the results between the two groups.
By comparing these results with a second group that did not undergo the intervention, we can infer what effects the intervention had on the initial group. Experimental studies often include a placebo control, where the participants who received the intervention may feel more motivated due to the name “treatment”, but the actual content is usually a simple activity like listening to a story or doing exercises.
The reason why this is important to know is so that you can distinguish true interventions from false ones! For example, many people claim that drinking green tea will help prevent cancer, so it is impossible to do an adequate test of the effectiveness of green tea without using a control group.
They use a control and a treatment
A control is something that is measured before being experimented upon, and then researchers see what effect it has on the experiment. For example, if you were to test the best way to bake a cake, your control would be just baking a plain vanilla layer cake.
After experimenting with the experimental recipe, they compare the results of the experiment using the normal control group to make sure that there was no difference in the result. If there is a difference, then the experiment worked and we can conclude that the addition part played in the success of the experiment.
The added ingredient helped achieve the desired outcome!
If you want to learn more about experiments, read our article: Tips for Aspiring Experiments Professionals. It covers some important things like how to create an experiment, and tips for conducting experiments.
They use multiple samples for the experiment
In experimental science, we are always trying to determine if one thing is better than another or different things are more effective. This testing can be done in two ways: A controlled test or observational tests.
A controlled test is when there is only one sample that gets experimented upon. For example, you may want to know which toothpaste is the best because your dentist suggested it as a solution for yours teeth. You would have to do a side-by-side comparison!
Observational tests are going up against something else already. For instance, you could compare popular brands with a new brand and see which one people seem to prefer. Or you could go to a store and just pick up a pack yourself to see how well they work.
Both of these methods need to be verified by another method. This way, no matter what results someone obtains, there is at least one other source confirming them!
Experts will sometimes combine both types of experiments together to get a more reliable result. These experts are called statisticians and they make sure that everything being used in the experiment functions properly and gives accurate results.
They also take into account any discrepancies in the results of each individual test so that you don’t have to repeat the experiment several times to get a true picture.
They use a sample, a control, and a treatment
A lot of experiments have you perform a certain action like cutting off your leg or putting sugar in the water to make it explode. If the experiment ends with no explosion, then they call that result a failure.
That is not what happened in our example above!
When scientists run into a situation where there was a failed experiment, they repeat the process using another sample, test, and treatment until they get a successful outcome.
This is how they can conclude that the original experiment worked. They do this by comparing the results between the two experiments and determining which one works better.
They use a control and a treatment
A control is something like testing theory against no theory at all. If you remember from chapter two, when we discussed experiments, you learned that scientists often use a simple experiment to test whether or not there is water in a certain container.
They put a small amount of liquid in one container and verify that it seeps out the bottom as dryness. Then they add more liquid until it overflows and some of the liquid drips down off the side. This goes on until the level of liquid in both containers is the same.
At this point, you can determine with 100% certainty that there is water in the second container. The first one proved false because it had shown signs of having water earlier!
That is what a control experiment does. It tests your hypothesis by adding onto your theory instead of taking away anything. In other words, if your theory says that sugar makes people hungry, then a control experiment would test that theory by eating just enough food without any added sugars.
A scientific experiment is similar to a control experiment in that only things are changed, but not taken away. For example, let’s say I want to know how fast a car will go around a track. So, I pick up the car and place it next to another car so that I can watch them both speed around the same course.
This way, I can compare their speeds directly without changing anything else.
They repeat the experiment until they are confident in the results
In experiments that test whether or not A leads to B, scientists usually try to replicate the study as much as possible. This is important because there may be some chance of A leading to B by coincidence.
For example, if researchers wanted to determine how well red cars draw attention, they would have to test this theory against all other colors.
They would also need to do their tests during daytime and at night so that people can relate to the findings. Only then would it be considered valid.
Furthermore, when doing the experiment, you must make sure that everything else remains the same! For instance, if the researcher was testing whether having lunch makes you feel better, he/she would have to make sure that everyone is hungry before the experiment and that nothing changes for the rest of the day.
This is done to rule out external factors like hunger making the participant feel better or worse.
They perform quality control
Another way to ensure that your experiment has good precision is by performing quality control (QC). This is done at different stages of experimentation to make sure that everything is working properly. For example, if you were doing research and testing whether or not sugar makes people feel happier, you would need to test that your source of sugar was indeed making people feel happy. You could check this by having someone else conduct the same experiment, using the same source of sugar as yours.
One way to do this is to have them do the exact same thing you did but in reverse. If their experiment shows that sugar made them feel happier, then your experiment must be wrong because theirs worked. However, if they didn’t feel any better after eating the sugar, then your experiment may work.
By checking for consistency throughout all stages of your experiment, we can rule out anything other than sugars effect on happiness.