OCR A-Level Psychology H567
Research Methods and Techniques
Planning and Conducting Research
Data Recording, Analysis and Presentation
Report Writing and Scientific Communication
Practical Activities and the Nature of Science
Mathematical Requirements for Research Methods
Studying and Evaluating the Core Studies: The Common Framework
Core Studies: Social Area
Core Studies: Cognitive Area
Core Studies: Developmental Area
Core Studies: Biological Area
Core Studies: Individual Differences Area
Areas and Perspectives in Psychology
Debates in Psychology
Practical Applications of Psychology
Issues in Mental Health
Child PsychologyApplied option
Criminal PsychologyApplied option
Environmental PsychologyApplied option
Sport and Exercise PsychologyApplied option
Methodological Issues and Debates Running Through Applied Psychology
Mathematical Requirements for Research Methods
Critical values and deciding whether a result is significant
- 4 things to know
- Component 01
Overview
Recall questions on what a critical value is, the information needed to find one, one-tailed and two-tailed values, which tests need calculated values below or above the critical value, and deciding significance for Wilcoxon, chi-square and Mann-Whitney results.
What you need to know
Answer each one before you reveal it.
A chi-square test gives a calculated value of 4.10 against a critical value of 5.99 at p ≤ 0.05. What is concluded?
A Mann-Whitney U test yields U = 23 with a critical value of 27. State the outcome.
Which three pieces of information are needed to find a critical value in a table?
Questions from this subtopic
Each one with the model answer underneath.
- 1
What is a critical value?
Model answer
The value taken from a table of critical values against which the calculated value of a test is compared in order to decide significance.
- 2
Which three pieces of information are needed to find a critical value in a table?
Model answer
The number of participants or the degrees of freedom, the chosen level of significance, and whether the hypothesis is one-tailed or two-tailed.
- 3
When is a one-tailed critical value used?
Model answer
When the hypothesis is directional, that is when it predicts which way the difference or relationship will go.
- 4
Why is it harder to obtain a significant result with a two-tailed test?
Model answer
The chance of error is shared between both directions, so the critical value is more demanding than for a one-tailed test at the same level.
- 5
For which tests must the calculated value be equal to or lower than the critical value to be significant?
Model answer
The Mann-Whitney U test, the Wilcoxon signed ranks test and the binomial sign test.
- 6
For which tests must the calculated value be equal to or greater than the critical value to be significant?
Model answer
The chi-square test and Spearman's rho.
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