Hypotheses: directional and non-directional.

What is a Directional Hypothesis?

• Hypothesis stating specific direction of expected results.

What is another Name for Directional Hypothesis?

• One-tailed hypothesis.

Why is it called a Directional Hypothesis?

• Direction of effect is predicted.

Example of a Directional Hypothesis

• “Participants listening to classical music will score higher on memory test than participants listening to no music.”.

What words are commonly used in Directional Hypotheses?

• Higher.
• Lower.
• More.
• Less.
• Increase.
• Decrease.

What is a Non-directional Hypothesis?

• Hypothesis predicting relationship or difference but not direction of results.

What is another Name for Non-directional Hypothesis?

• Two-tailed hypothesis.

Why is it called a Non-directional Hypothesis?

• Direction of effect is not predicted.

Example of a Non-directional Hypothesis

• “There will be difference in memory scores between participants listening to classical music and participants listening to no music.”.

When are Directional Hypotheses usually used?

• When previous research or theory suggests likely outcome.

Why are Directional Hypotheses used when Previous Research exists?

• Researcher already has reason to expect specific direction of results.

When are Non-directional Hypotheses usually used?

• When little previous research exists or findings are inconsistent.

Why are Non-directional Hypotheses used when Previous Research is Limited?

• Researcher cannot confidently predict direction of results.

Why should Variables in Hypotheses be Operationalised?

• Variables must be clearly measurable and testable.

Example of a Weak Hypothesis

• “Exercise affects mood.” because variables are vague and not measurable.

Example of a Strong Directional Hypothesis

• “Participants exercising for 30 minutes will report lower stress scores than participants exercising for 5 minutes.” because variables are operationalised and direction predicted.

Difference between Directional and Non-directional Hypotheses

• Directional hypotheses predict specific direction of effect.
• Non-directional hypotheses predict effect or difference without stating direction.

Difference between One-tailed and Two-tailed Hypotheses

• One-tailed hypotheses predict direction of effect.
• Two-tailed hypotheses do not predict direction of effect.