What Is a Real Hypothesis?

A hypothesis is a tentative statement that proposes a possible explanation to some phenomenon or event. A useful hypothesis is a testable statement which may include a prediction.

When Are Hypotheses Used?

The key word is testable. That is, you will perform a test of how two variables might be related. This is when you are doing a real experiment. You are testing variables. Usually, a hypothesis is based on some previous observation such as noticing that in November many trees undergo colour changes in their leaves and the average daily temperatures are dropping. Are these two events connected? How?

Any laboratory procedure you follow without a hypothesis is really not an experiment. It is just an exercise or demonstration of what is already known.

How Are Hypotheses Written?

  1. Chocolate may cause pimples.
  2. Salt in soil may affect plant growth.
  3. Plant growth may be affected by the color of the light.
  4. Bacterial growth may be affected by temperature.
  5. Ultra violet light may cause skin cancer.
  6. Temperature may cause leaves to change color.

All of these are examples of hypotheses because they use the tentative word “may.”. However, their form is not particularly useful. Using the word may does not suggest how you would go about proving it. If these statements had not been written carefully, they may not have even been hypotheses at all. For example, if we say “Trees will change color when it gets cold.” we are making a prediction. Or if we write, “Ultraviolet light causes skin cancer.” could be a conclusion. One way to prevent making such easy mistakes is to formalize the form of the hypothesis.

Formalized Hypotheses example: If the incidence of skin cancer is related to exposure levels of ultraviolet light , then people with a high exposure to uv light will have a higher frequency of skin cancer.

If leaf color change is related to temperature , then exposing plants to low temperatures will result in changes in leaf color.

Notice that these statements contain the words , if and then. They are necessary in a formalized hypothesis. But not all if-then statements are hypotheses. For example, “If I play the lottery, then I will get rich.” This is a simple prediction. In a formalized hypothesis, a tentative relationship is stated. For example, if the frequency of winning is related to frequency of buying lottery tickets. “Then” is followed by a prediction of what will happen if you increase or decrease the frequency of buying lottery tickets. If you always ask yourself that if one thing is related to another, then you should be able to test it.

Formalized hypotheses contain two variables. One is “independent” and the other is “dependent.” The independent variable is the one you, the “scientist” control and the dependent variable is the one that you observe and/or measure the results. In the statements above the dependent variable is underlined and the independent variable is underlined and italicized.

The ultimate value of a formalized hypothesis is it forces us to think about what results we should look for in an experiment.

For the “If, Then, Because” hypothesis…you would use: “IF pigs and humans share the same nutritional behaviors, THEN their internal organs should look relatively the same BECAUSE of similar function and composure.” That is an example. For the “If, Then, Because” you should follow this guideline:

IF X and Y both do or share this, THEN this should be found/confirmed, BECAUSE of this fact or logical assumption.

Question: How does the type of liquid (water, milk, or orange juice) given to a plant affect how tall the plant will grow?
Hypothesis: If the plant is given water then the plant will grow the tallest because water helps the plant absorb the nutrients that the plant needs to survive.

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14 Comments on "How to Write Hypothesis for Lab Report"

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@keisha your lab hypothesis should have been written before the experiment. The purpose of the hypothesis was to create a testable statement in which your experimental data would either support or reject. Having a hypothesis based on a logical assumption (regardless of whether your data supports it) is still correct. If there is a disagreement between your hypothesis and experimental data it should be addressed in the discussion. So you can go ahead an choose a hypothesis for either increase or decrease of adipogenesis after the inducement of insulin and not be wrong….as long as it is correctly formatted (see… Read more »

Hey, I am having trouble writing my hypothesis.. I am supposed to write a hypothesis about how much adipogenesis was produced after the inducement of insulin. However, after proceeding with the experiments the results were On/Off .. meaning it will increase, decrease, increase, etc.. so it wasnt a constant result. It was supposed to be increasing.

please help!!!


this is very helpful but i don’t know how i would structure my hypothesis. i’m supposed to come up with a hypothesis related to the topic ‘how does mass effect the stopping distance of a cart?’. Could you help?


Thank you so much, it really help alot.:)

Zi Xang


This is a rather difficult usage of this construct. It would most likely follow

“If the empirical formula of (enter compound’s name) is (enter compound’s formula) then it would be expected that combustion of _________ would yield _________, because (enter your rationale)

Need more background info.


For the “If, then, because” hypothesis I am doing an experiment to determine the empirical formula by using combustion but I am unsure on how to formulate the hypothesis using this structure.


Thanks, really helpful.
Just one question, what about the ‘because’ part? right after the ‘if’ and ‘then’ parts?


I really need help for onion skin lab hypothesis for class