When analyzing categorical data from an observational study or investigation, psychologists often use the Chi-squared (χ2\chi^2χ2) test of association. The formula used to calculate this test statistic is:
χ2=∑(O−E)2E \chi^2 = \sum \frac{(O - E)^2}{E} χ2=∑E(O−E)2What does E E\,E represent in this formula?
The observed frequency of participants or behaviors recorded in each category.
The effect size of the relationship between the two categorical variables.
The expected frequency for each cell of the contingency table, assuming the null hypothesis is true.
The experimental error or standard error of the mean for the nominal data.
513 exam-style questions on OCR A Level Psychology Data recording, analysis and presentation. Each one has a worked solution and a mark scheme showing where the marks go.