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Chi-Square Test of Independence. Purpose: Test whether two nominal variables are related Design: Individuals categorized in two ways. Assumptions. Mutually exclusive groups Expected frequencies at least 5 per cell. Formula for Chi-Square. Example.
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Chi-Square Test of Independence • Purpose: Test whether two nominal variables are related • Design: Individuals categorized in two ways
Assumptions • Mutually exclusive groups • Expected frequencies at least 5 per cell
Example Males and females were categorized on whether they were right or left-handed. Is there a significant relationship between handedness and gender?
Observed Frequencies FEMALE MALE LEFT 10 10 RIGHT 25 20
FEMALE MALE R LEFT 10 10 20 RIGHT 25 20 45 C 35 30 STEP 1: Find Row and Column totals.
LEFT, FEMALE RIGHT, FEMALE LEFT, MALE RIGHT, MALE
STEP 3: For each group, compute (fo-fe)2 and divide by fe.
LEFT, FEMALE RIGHT, FEMALE LEFT, MALE RIGHT, MALE
STEP 4: Add up the results across all groups to get the chi-square. 2 = .06+.02+.06+.03 = .17
STEP 5: Look up 2crit in table, using df = (rows-1)(columns-1). df = (2-1)(2-1)=1 2crit = 3.84
STEP 6: Compare your c2 to the critical value. 2 = .17 2crit = 3.84
APA Format Sentence A chi-square test of independence showed no significant relationship between handedness and gender, 2 (1, N = 65) = 0.17, p > .05.