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Scientific Method

3. The Hypothesis
Now, once you have decided on your question and performed your background research, the next important step is to propose a possible answer to the question. This process is known as "formulating the hypothesis". The hypothesis should always show how two different factors are related to one another. For example, in the example above, we asked "Do sunscreen lotions with a higher SPF rating offer better protection?"

What the Dictionary says

hy·poth·e·s is n. pl. hy·poth·e·ses (-s z )
  • A tentative explanation for an observation, phenomenon, or scientific problem that can be tested by further investigation
  • Something taken to be true for the purpose of argument or investigation; an assumption
  • The antecedent of a conditional statement
(don't worry if the above definitions are too difficult for you to understand! You'll get the hang of it as you progress through the pages of this guide!)
The two relating factors are (1) the SPF rating of sunscreen lotion, and (2) the level of protection. The hypothesis for your question would therefore be "Sunscreen lotions with a higher SPF rating are able to block a larger amount of UV radiation from the sun, and therefore provide better protection."

For the investigative science project, it is important to have a hypothesis that can be proved or disproved, and one that can be measured. One way of ensuring that your hypothesis is measurable is to see if you can identify the following variables for your science project:
The independent variable
This is the variable that changes throughout the experiment. You will change this variable intentionally in order to see how it affects the other variable known as the dependent variable. In our sample experiment, the SPF rating is the independent variable that would be "changed" by introducing sunscreen lotions of different SPF ratings.
The idependent variable
The dependent variable changes in response to the independent variable. In our example, the level of protection would be the dependent variable, as it would change depending on the SPF rating. At this stage, you will then ask "How do I measure the level of protection?". Your background research will reveal that the level of UV radiation can be measured using a UV meter.
The control variables
The variables that are not changed are called control variables. In the example above, the independent variable is the SPF rating, and the dependent variable is the level of UV radiation measured. Some of the control variables would be the brand of sunscreen lotion used (you should use sunscreens of the same brand, but of different SPF ratings), the quantity of sunscreen lotion used for each experiment, the type of materials and the type of UV meter used for each experiment. In a control, all variables are identical to the original experiment, except for the independent variable. The variables that are identical in both the original experiment and the control are called the control variables.

An example hypothesis

Let's look at the following example:-


Medicine and Health > Dermatology


Do sunscreen lotions with a higher SPF rating offer better protection?


Sunscreen lotions with a higher SPF rating are able to block a larger amount of UV radiation from the sun, and therefore provide better protection.
When preparing your hypothesis, you should state facts from your past observations and experience, which led you to the hypothesis. In the example above, you may have based your hypothesis on the fact that lotions with higher SPF ratings are more expensive, or from the claims made by the manufacturers on TV advertisements or in brochures.

Remember, once you write down your hypothesis, you should not change it, no matter how tempting it may be to do so! Real scientists go all the way to either prove or disprove their own hypothesis! It's perfectly all right to go through the entire experiment only to find that your hypothesis has been disproved. You can still score top marks for your project, as long as you properly recorded your results and don't miss any steps. The judge is primarily interested in whether you correctly used the scientific method.

So again - there will be times when you will prove yourself wrong, and that's perfectly fine. That's what scientific discovery is all about!

What is the difference between fact, theory and hypothesis?

To most people, a theory is just a vague and fuzzy sort of fact, and the term "hypothesis" is often used as a fancy word for a "guess". However, to the true scientist, a theory is a conceptual framework that explains why things are the way they are (observations), and also predicts new explanations and observations.

For instance, imagine you are watching the sun rise. This is an observation which is explained by the theory of gravity proposed by Newton. This theory explains many phenomena such as the path followed by the sun as it moves across the sky, and the phases of the moon and the tides. Today, you can use this theory to perform amazing calculations, and to predict the actual position of the sun, the phases of the moon, and even guide a space shuttle across the Solar System!

How useful is the scientific method?

If you stop to think about it, you will realize that the scientific method is also useful in everyday problem-solving. For example: How do you find out the reason that your internet connection is down? Is it due to a disconnected cable? Or perhaps your modem is broken? Maybe your internet service provider is down? The process you go through to solve this problem could very well involve scientific thinking, and the results might contradict your initial guess!
A hypothesis is better described as a "working assumption". A scientist usually comes up with a hypothesis and then checks if it ``holds water'' by testing it in experiments. If the hypothesis is proven to be true, the scientist declares it to be a theory.

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