What is a scientific hypothesis?

A scientific hypothesis is a tentative, testable explanation for a phenomenon. It's the beginning of the scientific method. Many people describe it as an educated guess. A hypothesis is more informed than a guess. While an educated guess suggests a random prediction based on a person's expertise, developing a hypothesis requires active observation and background research.
There is no preset outcome in a hypothesis. A scientific hypothesis is an idea that can be supported or rejected through carefully crafted experimentation or observation. In his famous book "The Logic of Scientific Discovery", Austrian-British philosopher Karl Popper advanced the concept of falsifiability and testability.

Predicting the results of future experiments is a key function of a hypothesis.

A hypothesis is usually written in the form of an if-then statement, which gives a possibility and explains what may happen. California State University, Bakersfield said that the statement could include "may".

There are some examples of hypothesis statements.

A dog that is given garlic every day will not get fleas.
People who eat a lot of candy are more likely to have dental problems.
If ultraviolet light can cause damage to the eyes, then maybe it can cause blindness.

A hypothesis that is useful should be able to be tested. It should be possible to prove it wrong. Karl Popper's book "Conjectures and Refutations" states that a theory can't be proved wrong.

An untestable statement is, "dogs are better than cats." The definition of "better" is not clear. Untestable statements can be reworded to make them testable. "Owning a dog is associated with higher levels of physical fitness than owning a cat." The researcher can compare the fitness of dog and cat owners with this statement.

There are different types of scientific hypotheses.

There will be no difference in spin speed between a turbine with 6 versus 8 blades. The image is courtesy of SDI productions.

Researchers usually state their hypotheses in two different ways. There will be no relationship between the variables tested and the experimental groups according to the null hypothesis. There will be a difference between the experimental groups according to the alternative hypothesis. According to the University of Miami, this is the hypothesis scientists are most interested in.

A null hypothesis states that there will be no difference in the rate of muscle growth between people who take a supplement and those who don't. There will be a difference in the rate of muscle growth between people who take a supplement and those who don't.

The null hypothesis has been rejected in favor of the alternative hypothesis if the experiment shows a relationship between the variables.
There are more than one way to describe an alternative hypothesis. There will be a difference between the two groups if the alternative hypothesis is correct. A two-tailed hypothesis is a type of prediction. A one-tailed hypothesis is a hypothesis that says that people who take a supplement will gain more muscle than people who don't.

During an experiment, there can be errors. There are two ways in which these errors can happen. A type I error is when the null hypothesis is rejected. This is also called a false positive. When the null hypothesis is not rejected, there is a type II error. The University of California, Berkeley says this is a false negative.
A hypothesis can be rejected or changed, but it can never be proved correct. A scientist can make a hypothesis that a certain type of tomato will be red if it has a red gene. The scientist discovered that each tomato of this type is red. There is a possibility that there is a tomato of that type in the world. The hypothesis may not be true 100% of the time.

Scientific hypothesis and scientific theory.

Simple hypotheses are the best. They deal with a small set of phenomena. Theories are generally combined into a general explanation for a wide range of phenomena, according to the University of California, Berkeley. If animals adapt to suit their environments, birds that live on islands with lots of seeds to eat will have different shaped beaks than birds that live on islands with lots of insects to eat. Charles Darwin formulated the theory of evolution by natural selection after testing many hypotheses.

ories are the ways in which we make sense of what we see in the natural world. ories are structures of ideas that explain.
There are additional resources.

There is a bibliography.

The Encyclopedia Britannica. There is a scientific hypothesis. January 13, 2022.

"The Logic of Scientific Discovery" was written by Karl Popper.

California State University, Bakersfield, "Formatting a testable hypothesis."
"Conjectures and Refutations" was written by Karl Popper.

The second Canadian edition of research methods of psychology was published.

The University of Miami has a book called "The Scientific Method".
William M.K. Trochim has a research methods knowledge base.
The University of California, Berkeley has a lecture on Multiple Hypothesis Testing and False Discovery Rate.
"Science at multiple levels" is an article by the University of California, Berkeley.