Bivariate Analysis: Chi-Square, Fisher, and McNemar Tests

Question 1

What is a Chi-Square Test?

Answer 1

Nominal or Dichotomous Variable, compared across 2 discrete independent groups
HOMOGENEITY

Question 2

What is a Fisher’s Exact Test?

Answer 2

Dichotomous variable, compared two discrete independent groups

Question 3

What is a McNemar Test?

Answer 3

Dichotomous variable, compared across Matched Measurements in two discrete dependent groups
PRE/POST

Question 4

What is the Chi-Square Test of Homogeneity

Answer 4

Applied to a nominal variable from two or more different groups/populations to determine whether frequency counts are distributed identically across the groups

Question 5

If a nominal variable is dichotomous, it means what?

Answer 5

There are ONLY two options
ex. improved vs not improved

Question 6

For the Chi-Square Test of Homogeneity, the H0 compared what?

Answer 6

H0 = Pt = Pc
Proportion of patients with specific outcome will be EQUAL between treatment and comparison group
COMPARING PROPORTIONS NOT means

Question 7

A large X^2 value in a Chi-Square tests = statistically significant, what can increase the value of x^2?

Answer 7

The larger the difference in proportions = greater x^2

Question 8

A Chi-Square test is ONE directional with an alpha of 0.05 and a df =1, what is the the critical value?

Answer 8

3.84

Question 9

What are the requirements/details of the Fisher’s Exact Test?

Answer 9

1. More conservative than x^2, less chance of a false positive
2. For 2x2 tables ONLY
3. N<20 or if there are <5 in one of the cells

Question 10

What is the Chi-Square Test of Independence?

Answer 10

Applied to 2 nominal variables from one group/population to determine whether frequency counts are distributed in a manner that shows an association between the two variables

Question 11

What does Independence mean?

Answer 11

One variable does not say anything about another variable

Question 12

What is the H0 and HA of the Chi-Square Independence Test?

Answer 12

H0: No association
HA: Association

Question 13

What are the parameters of the Chi Square Independence Test?

Answer 13

1. ONE Population
2. TWO Dichotomous Variables
3. FREQUENCY = ASSOCIATION

Question 14

What are the requirements/details of the McNemar Test?

Answer 14

1. Dependent groups, paired data
2. Dichotomous variables, 2x2
3. Compare proportions between PAIRED data