Aims + Hypotheses

research aims: the stated intentions of a study, to be clear about the purpose + often based on findings of past research

alternative hypothesis: a statement of the relationship between the IV and DV + based on previous research and shows a difference

null hypothesis: a prediction that states no difference or relationship

directional hypothesis: states which set of scores will be faster/better/postively/negatively correlated

non-directional hypothesis: states there will be a difference/relationship but no direction

S T E P S TO W R I T I N G A H Y P O T H E S E S

STEP 1 — Identify the variables

Find:

• IV = what is being changed/compared

• DV = what is being measured

Example:

Investigate whether caffeine consumption affects memory performance.

IV: caffeine consumption
DV: memory performance

STEP 2 — Operationalise BOTH variables

Make them specific and measurable.

Instead of:

I V = caffeine ❌
DV = memory❌

Write:

IV = 0mg vs 200mg of caffeine
DV = number of words correctly recalled from a 20-word list

Now another researcher knows EXACTLY what you're changing and measuring.

STEP 3 — Decide what type of hypothesis you're writing

Ask:

Am I predicting a direction?

If YES → directional hypothesis

If NO, but you're predicting a difference/relationship → non-directional (alternative) hypothesis

If you're predicting no difference/relationship → null hypothesis

STEP 4 — Write the hypothesis

If it's DIRECTIONAL:

Use:

Participants who [IV condition 1] will [higher/lower/faster/slower/etc.] [DV] than participants who [IV condition 2].

Example:

Participants who consume 200mg of caffeine will recall more words than participants who consume 0mg of caffeine.

You've predicted which way the result will go. ✅

↔ If it's NON-DIRECTIONAL / ALTERNATIVE:

Use:

There will be a significant difference in [DV] between participants who [IV condition 1] and participants who [IV condition 2].

Example:

There will be a significant difference in the number of words recalled between participants who consume 200mg of caffeine and participants who consume 0mg.

You predict a difference, but you don't say which group will perform better. ✅

🚫 If it's NULL:

Use:

There will be no significant difference in [DV] between participants who [IV condition 1] and participants who [IV condition 2].

Example:

There will be no significant difference in the number of words recalled between participants who consume 200mg of caffeine and participants who consume 0mg.

You're predicting nothing significant will happen. ✅