Chi-square

Question 1

basic idea of chi square

Answer 1

compares observed count to expected count

Question 2

measure of error =

Answer 2

(observed - expected)^2/expected

Question 3

contingency table analysis

Answer 3

when 2+ categorical variables and interested to see if there is some kind of association between those variables

Question 4

chi-square test for independence

Answer 4

often research interest in two or more categorical variables each having two or more categories

if no relation between variables, they’re called independent

Question 5

for chi square test of independence need to create

Answer 5

contingency table

Question 6

null and alternative for chi square test of association

Answer 6

H0: two (categorical) variables are independent
Ha: two (categorical) variables are associated

Question 7

assumptions of chi-square tests

Answer 7

• Both variables are categorical.
• Observations are randomly sampled from the population(s).
• Observations are independent
• Each observation is in exactly one category per variable. (no overlapping categories)
• Sample sizes are large, with E(Fe) at least 5 for every cell

Question 8

contingency table does what

Answer 8

contrasts observed frequencies in each cell of a contingency table with expected frequencies

Question 9

Fisher’s exact test

Answer 9

• Useful where chi-square test is inappropriate because E(Fe)