Hypotheses

What is the aim of an investigation?

The intended purpose of the investigation i.e. what it is actually trying to discover.

• For example: to investigate whether energy drinks makes people more talkative

Why do research investigations need an aim?

To give a clear focus.

What do researchers need to do once they’ve written their aim?

Formulate a hypothesis (which clearly states the relationship between variables as stated by the theory)

What is a hypothesis?

A clear, testable statement. It makes a general prediction about what will happen in an experiment - usually about how the IV will affect the DV. Stated at the start of any study.

What is the difference between aims and hypotheses?

Aims are an initial statement of what the researcher plants to investigate whereas the hypothesis is a formal and testable statement of the relationship between variables.

What are the 2 types of hypotheses?

Null hypothesis and alternative hypothesis.

What is null hypothesis?

Predicts that there will be no difference or relationship (any results found are due to chance). Any difference found is due to chance.

• For example: there will be no difference in memory scores between people who listen to music and those who do no

What is alternative hypothesis?

Predicts that the IV will have an effect on the DV (that something will change or there will be a difference). The opposite of null hypothesis. It’s what the researcher expects to find.

What are the 2 types of alternative hypotheses?

Directional and non-directional.

What is directional hypothesis? (one-tailed)

Predicts the direction of the expected effect or difference. It tells you how one variable will affect the other - whether it will increase, decrease, improve or worsen.

• Used when there is previous research suggesting what direction the results will go in - good reason to expect a certain outcome

• For example: People who listen to music will remember more words than those who do not

What is non-directional hypothesis? (two-tailed)

Predicts there will be a difference or relationship, but doesn’t state what direction it will go in - basically saying ‘something will change, but we’re not sure which way’.

• Used when there is little or no previous research to suggest what the outcome will be, or if the evidence from past studies is mixed

• For example: There will be a difference in memory scores between people who listen to music and those who do not.

How do psychologists decide which type of hypothesis to use?

• They tend to use a directional hypothesis when the findings of previous research studies suggest a particular outcome

• When there is no previous research, or when findings from earlier studies are contradictory they will instead decide to use non-directional hypothesis