Scientific Method Tutorial and Review, Practice Questions

Most  nursing school entrance exams have a section for scientific method and scientific reasoning.

Below are scientific method and reasoning practice test questions.

Scientific Method Tutorial   —   Practice Questions   —   Answer Key   — Common Mistakes and Misconceptions

Tutorial and Quick Review

The scientific method is a set of steps that allow people who ask “how” and “why” questions about the world to go about finding valid answers that accurately reflect reality.

Were it not for the scientific method, people would have no valid method for drawing quantifiable and accurate information about the world.

The scientific method is a systematic approach to investigating a scientific problem. It involves making observations, forming a hypothesis, testing the hypothesis with experiments, analyzing the results, and drawing conclusions.

There are four primary steps to the scientific method:

1. Analyzing an aspect of reality and asking “how” or “why” it works or exists
2. Forming a hypothesis that explains “how” or “why”
3. Making a prediction about the sort of things that would happen if the hypothesis were true
4. Performing an experiment to test your prediction.

These steps vary somewhat depending on the field of science you happen to be studying.  (In astronomy, for instance, experiments are generally eschewed in favor of observational evidence confirming that predictions are true.)  But for the most part this is the model scientists follow.

Some Scientific Method Definitions

Control Group
A control group is a group that is not used in the experiment. It is used to compare the results of the experimental group to determine if the independent variable has an effect.

Variable
A variable is any factor that can change in an experiment. There are two types of variables in an experiment: independent and dependent.

Independent Variable
An independent variable is the variable that is changed to observe its effect on another variable.

Dependent Variable
A dependent variable is the variable that is being measured in the experiment to see if it is effected by the independent variable.

Data
Data is information collected during an experiment or observation.

Conclusion
A conclusion is a statement or inference drawn from the results of an experiment. It summarizes what was learned from the experiment and whether or not the hypothesis was supported.

Replication
Replication is the repetition of an experiment to verify the results. Replication helps to establish the reliability and validity of the results.

The first step in the scientific method requires you to determine what it is about reality that you want to explore. 

You might notice that your friends who eat regular servings of fruits and vegetables are healthier and more athletic than your friends who live off red meat and meals covered in cheese and gravy.  This is an observation and, noting it, you are likely to ask yourself “why” it seems to be true.  At this stage of the scientific method, scientists will often do research to see if anyone else has explored similar observations and analyze what other people’s findings have been.  This is an important step not only because it can show you what others have found to be true about their observation, but because it can show what others have found to be false, which can be equally as valuable.

After making your observation and doing some research, you can form your hypothesis.  A hypothesis is an idea you formulate based on the evidence you have already gathered about “how” your observation relates to reality. 

Using the example of your friends’ diets, you may have found research discussing vitamin levels in fruits and vegetables and how certain vitamins will affect a person’s health and athleticism.  This research may lead you to hypothesize that the foods your healthy friends are eating contain specific types of vitamins, and it is the vitamins making them healthy.   Just as importantly, however, is applying research that shows hypotheses that were later proven wrong.  Scientists need to know this information, too, as it can help keep them from making errors in their thinking.  For instance, you could come across a research paper in which someone hypothesized that the sugars in fruits and vegetables gave people more energy, which then helped them be more athletic.  If the paper were to go on to explain that no such link was found, and that the protein and carbohydrates in meat and gravy contained far more energy than the sugar, you would know that this hypothesis was wrong and that there was no need for you to waste time exploring it.

The third step in the scientific method is making a prediction based on your hypothesis. 

Forming predictions is vital to the scientific method because if your prediction turns out to be correct, it will demonstrate that your hypothesis can accurately explain some aspect of the world.  This is important because one aspect of the scientific method is its ability to prove objectively that your way of understanding the world is valid.  We can take the simple example of a car that will not start.  If you notice the fuel gauge is pointing towards empty, you can announce your prediction to the other passengers that a careful test of the gas tank will show the car has no fuel.  While this seems obvious, it is still important to note since a prediction like this is the only way to really prove to your friends that you understand how a fuel gauge works and what it means.

In the same way a prediction made by a hypothesis is the only way to really show that it represents reality.  For instance, based on your vitamin hypothesis you may predict people can be healthy and athletic while eating whatever they want as long as they take vitamin supplements.  If this prediction ends up being true, it will show that it is in fact the vitamins, and only the vitamins, in fruits and vegetables that make people healthy and athletic.  It will prove that your hypothesis shows how vitamins work.

The final step is to perform an experiment that tests your prediction. 

An experiment is a scientific procedure used to test a hypothesis. It involves manipulating one variable to observe the effect on another variable.

You may decide to separate your healthy friends into three groups, give one group vitamin supplements and prohibit them from eating vegetables, give another fake supplements and prohibit them from eating vegetables and have the third act normally as the control group.  It is always important to have a control group so you have someone acting “normally” to compare your results against.  If this experiment shows the real supplement group and the control group maintaining the same level of health and athleticism while the fake supplement group grows weak and sickly, you will know your hypothesis is true.  If, on the other hand, you get unexpected results, you will need to go back to step one, analyze your results, make new observations and try again with a different hypothesis.

Any hypothesis that cannot be confirmed with experiment (or in the case of fields such as astronomy, with observation) cannot be considered true and must be altered or abandoned.  It is in this stage where scientists—being humans, with human beliefs and prejudices—are most likely to abandon the scientific method.  If an experiment or observation gives a scientist results that he or she does not like, the scientist may be inclined to ignore the results rather than reexamine the hypothesis.  This was the case for nearly a thousand years in astronomy with astronomers attempting to form accurate models of the solar system based on circular orbits of the planets and on Earth being in the center.  For philosophical reasons it was believed that circles were “perfect” and that the Earth was “important,” so no model that had the correct elliptical orbits or the sun properly in the center was accepted until the 16^th century, even though those models more accurately described all astronomers’ observations.

Scientific Method Practice Questions

1. When employing the scientific method of research, the researcher follows these steps:

a. Define the question, make observations, offer a possible explanation, perform an experiment, analyze data, draw conclusions.
b. Make observations, offer a possible explanation, define the question, perform an experiment, analyze, draw conclusions.
c. Perform an experiment, make observations, define the question, offer a possible explanation, analyze the data, draw conclusions.
d. Make observations, define the question, offer a possible explanation, perform an experiment, analyze data, draw conclusions.

2.  ________ _______ is a principle that generally advises choosing the competing hypothesis that makes the fewest new assumptions, when the hypotheses are equal in other respects.

a. Hickam’s Dictum
b. Boyle’s Law
c. Dalton’s Law
d. Occam’s Razor

3.  The  ___________ is the prediction that an observed difference is due to chance alone  and not due to a systematic cause; this hypothesis is tested by statistical analysis, and either accepted or rejected.

a. Null hypothesis
b. Hypothesis
c. Control
d. Variable

4.  In science, _________ is defined as a difference between the desired and actual performance or behavior of a system or object.

a. Accuracy
b. Uncertainty
c. Error
d. Mistake

5. In science, industry, and statistics, the __________ of a measurement system is the degree of closeness of measurements of a quantity to its actual (true) value.

a. Mistake
b. Uncertainty
c. Accuracy
d. Error

6. The interval of confidence around the measured value such that the measured value is certain not to lie outside this stated interval refers to the ___________ of that value.

a. Accuracy
b. Error
c. Uncertainty
d. Measurement

7.  _________, which refers to the repeatability of measurement, does not require knowledge of the correct or true value.

a. Precision
b. Value
c. Certainty
d. Accuracy

8.  In science, _________ refers to the disagreement between a measurement and the true or accepted value. 

a. Exactitude
b. Precision
c. Error
d. Inaccuracy

9.  The scientific term ____________ refers to a practical test designed with the intention that its results be relevant to a particular theory or set of theories.

a. Procedure
b. Variable
c. Hypothesis
d. Experiment

10.  A _________ ________ is an approximation or simulation of a real system that omits all but the most essential variables of the system.

a. Scientific method
b. Independent variable
c. Control group
d. Scientific model

Answer Key

1. A
When employing the scientific method of research, the researcher follows these steps: define the question, make observations, offer a possible explanation, perform an experiment, analyze data, draw conclusions.

2. D
Occam’s Razor is a principle that generally advises choosing the competing hypothesis that makes the fewest new assumptions, when the hypotheses are equal in other respects.

3. A
The prediction that an observed difference is due to chance alone and not due to a systematic cause; this hypothesis is tested by statistical analysis, and accepted or rejected is  the Null hypothesis

4. C
In science, Error is defined as a difference between the desired and actual performance or behavior of a system or object.

5. C
In science and engineering, the Accuracy of a measurement system is the degree of  closeness of measurements of a quantity to its actual (true) value.

6. C
The interval of confidence around the measured value such that the measured value is certain not to lie outside this stated interval refers to the uncertainty of that value.

7. A
Precision, which refers to the repeatability of measurement, does not require knowledge of the correct or true value.

8. B
In science, precision refers to the disagreement between a measurement and the true or accepted value.

9. D
The scientific term Experiment  refers to a practical test designed with the intention that its results be relevant to a particular theory or set of theories.

10. D
A scientific model is an approximation or simulation of a real system that omits all but the most essential variables of the system.

Misinterpreting the scientific process.   The scientific process is not simply a collection of facts found in textbooks, but an ongoing and dynamic inquiry.

Assuming science is complete.  Science has NOT discovered everything there is to know about the natural world. Science is an ongoing process.