Research Methods- Tests of association: Chi-Squared Flashcards
What is Chi-Squared used for?
Chi-Squared is a test of difference or association. The data are nominal and recorded as a frequency count of the categories.
What is the design of the study involving children aged 5 and 8?
The design is unrelated, with two independent groups of children. The level of measurement is nominal, as data is collected in the form of frequencies in two categories: ability to decentre or not.
What is the aim of the study on cognitive development?
The study aims to determine if there is a difference in children’s ability to decentre (see the world from the perspective of another) depending on their age. A group of 5-year-olds and 8-year-olds were given the three mountains task to see if they could choose a card corresponding to a doll’s view rather than their own.
What is the alternative hypothesis in the study?
The alternative hypothesis is that more 8-year-olds than 5-year-olds are able to select a card that represents a perspective different from their own. (directional, one-tailed).
What is the null hypothesis in the study?
The null hypothesis is that there is no difference between the number of 5-year-olds and 8-year-olds who can select a card that represents a perspective different from their own.
What is Step 1 in the Chi-Squared analysis?
Step 1 involves drawing a 2x2 contingency table showing the observed frequencies in each cell and calculating the totals for each row, each column, and the overall total.
What is Step 2 in the Chi-Squared analysis?
Step 2 involves calculating the expected frequencies (E) for each of the four cells in the 2x2 table. The expected frequency is calculated by multiplying the total for the row by the total for the column, divided by the grand total.
What is the purpose of calculating expected frequencies?
Expected frequencies represent the frequency that would be expected if there was no difference between the two groups (if the age of the child had no effect on their ability to decentre).
What is Step 3 in the Chi-Squared analysis?
Step 3 involves adding up the values in the final column to calculate the value of x². The calculated value of x² in this example is 23.1.
What is Step 4 in the Chi-Squared analysis?
Step 4 involves finding the critical value by calculating the degrees of freedom (df) as (rows - 1) × (columns - 1) = 1. The critical value of x² for a one-tailed test at the 0.05 level, where df = 1, is 2.71.
What conclusion is drawn from the Chi-Squared analysis?
Since the calculated value of x² (23.1) is more than the critical value (2.71), the null hypothesis is rejected, and the alternative hypothesis is accepted: There is a difference in the number of 5-year-olds and 8-year-olds who can select a card that represents a perspective different from their own (p≤0.05).
