MET 09 - Statistical Testing Flashcards
(19 cards)
What is statistical testing?
- Provides a way of determining whether hypotheses should be accepted or rejected
- By using a statistical test, we can find out whether differences or relationships between variables are significant (meaningful) or are likely to have occurred by chance
What is the sign test?
- A statistical test used to analyse the difference in scores between related items (e.g. the same participant tested twice)
- Data should be nominal or better
- It is a non-parametric
What is nominal data?
It is named data which can be separated into discrete categories which do not overlap
What is ordinal data?
It is data which is placed into some kind of order or scale
What is interval data?
It is data which is measured in fixed units with equal distance between points on the scale
What is a directional hypothesis?
States the direction of the difference or relationship
When should a directional hypothesis be used?
Researchers use a directional hypothesis when a theory or the findings of a previous research studies suggest a particular outcome
What is a non-directional hypothesis?
Does not state the direction of the difference or relationship
When should a non directional hypothesis be used?
Researchers use a non-directional hypothesis when there is no theory or previous research, or findings from earlier studies are contradictory
What is an experimental hypothesis?
States that there will be a significant change or difference in the outcome of the test/experiment
What is a null hypothesis?
- States that there will be no significant change or difference in the outcome of the test/experiment
- If there is a slight difference, then it won’t be big enough to confirm a significant change
What should be mentioned at the end of a null hypothesis?
Any difference will be due to chance
What are the conditiones that need to be met to use a sign test?
- We need to be looking for a differences rather than an association
- We need to have used a repeated measures design
- We need data that is organised into categories, known as nominal data
What features should be considered when choosing a statistical test?
- The level of measure
- The experiment design
- If you are looking for differences or correlations
- We need to know what type of hypothesis you have to decide if you accept or reject a hypothesis
What pieces of information are required when reading a table of critical values?
- The significance level (generally 0.05/5%)
- The number of participants in the investigation
- Whether the hypothesis is directional (one-tailed test) or non-directional (two-tailed test)
What is statistical signficance?
- Statistical significance helps quantify whether a result is likely due to chance or to some factor of interest
- When a finding is significant, it simply means you can feel confident that’s it real, not that you just got lucky (or unlucky) in choosing the sample or by other factors
What probability level is used in psychology? And what does it mean?
- 0.05
- It means there is a 5% chance of behaviour being down to chance/a blip/coincidence
When is a probability level of 0.05 not used?
- There are situations where researchers need to be more confident and so use 0.01 probability
- This might involve human cost, e.g. drug trials or if a study is a 1-off and won’t happen again
What is the statement of significance rule?
- The statistical table shows that for N = and at a significance level of 0.05 for a one/two tailed hypothesis for a sign test, the critical value is .
- As the calculated value of S is greater/less than the critical value, the result is/is not significant.
- Therefore, the experimental hypothesis can re rejected/accepted and the null hypothesis can be rejected/accepted.
