Q: What does 'significant at p < 0.05' mean?

It means there is less than a 5% probability that the observed results are due to chance alone. In other words, we can be 95% confident that the results reflect a real effect in the population. If the p-value is greater than 0.05, we accept the null hypothesis and conclude there is no significant effect.

Q: How do I write a hypothesis for a psychology experiment?

A hypothesis should be a clear, testable statement predicting the relationship between the IV and DV. For a directional (one-tailed) hypothesis, specify the direction (e.g., 'Participants who listen to music will recall more words than those who do not'). For a non-directional (two-tailed) hypothesis, simply state there will be a difference (e.g., 'There will be a difference in word recall between participants who listen to music and those who do not'). Always include operationalised variables.

Question 1

What is the difference between a lab experiment and a field experiment?

Accepted Answer

A lab experiment takes place in a controlled environment where the researcher manipulates the IV and controls extraneous variables. This increases internal validity but may lack ecological validity. A field experiment occurs in a natural setting, like a school or street, where the IV is still manipulated but participants are often unaware they're in a study. This boosts ecological validity but reduces control, making replication harder.

Question 2

How do I choose which inferential test to use?

Accepted Answer

You need to consider three things: the experimental design (independent groups, repeated measures, or matched pairs), the level of measurement (nominal, ordinal, or interval), and whether you're looking for a difference or a correlation. For example, if you have repeated measures and nominal data, use the sign test. For independent groups and nominal data, use chi-squared. For correlations with ordinal data, use Spearman's rho.

Question 3

What is a confounding variable and how do I control it?

Accepted Answer

A confounding variable is an extraneous variable that varies systematically with the IV, potentially affecting the DV and leading to a false conclusion. For example, if you test memory in the morning for one group and afternoon for another, time of day could confound results. Control methods include random allocation to groups, standardised procedures, counterbalancing, and using a single-blind or double-blind design.

Question 4

Why is random sampling often not used in psychology?

Accepted Answer

Random sampling involves selecting participants from a population so that everyone has an equal chance of being chosen. In practice, it's difficult because you need a complete list of the population (sampling frame), and even then, not everyone will agree to participate. Psychologists often use opportunity or volunteer sampling because they are more practical, even though they introduce bias.

Question 5

What does 'significant at p < 0.05' mean?

Accepted Answer

It means there is less than a 5% probability that the observed results are due to chance alone. In other words, we can be 95% confident that the results reflect a real effect in the population. If the p-value is greater than 0.05, we accept the null hypothesis and conclude there is no significant effect.

Question 6

How do I write a hypothesis for a psychology experiment?

Accepted Answer

A hypothesis should be a clear, testable statement predicting the relationship between the IV and DV. For a directional (one-tailed) hypothesis, specify the direction (e.g., 'Participants who listen to music will recall more words than those who do not'). For a non-directional (two-tailed) hypothesis, simply state there will be a difference (e.g., 'There will be a difference in word recall between participants who listen to music and those who do not'). Always include operationalised variables.

Research methods

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