Biostats 3 & 4

Question 1

What are different testing methods for categorical data

Answer 1

Chi2

Fisher’s exact

Question 2

What are the rules and assumptions of categorical data

Answer 2

data are arranged into categories
data are independent; random sample from the population
must be a positive integer >0

Question 3

What are the types of studies for categorical data

Answer 3

cross sectional
prospective
retrospective
experimental
diagnostic test

Question 4

What is a cross sectional study

Answer 4

recruit study group and define two categories

Question 5

What is a prospective study

Answer 5

recruit group with some difference and follow them

Question 6

What is a retrospective study

Answer 6

start with a condition and look backwards at potential causes

Question 7

What is an experimental study

Answer 7

recruit a group, manipulate variables

Question 8

What is a diagnostic test

Answer 8

positive and negative results

Question 9

When will a fisher’s exact test be used over chi2

Answer 9

when a sample group is <5

Question 10

What are the degrees of freedom

Answer 10

of variables in final calculation that are free to vary

Question 11

How is DOF calculated

Answer 11

usually n-1

df=(rows-1) X (columns-1)

Question 12

What is the use of Chi2

Answer 12

tests the goodness of fit; observed frequency compared to theoretical

Question 13

What does a student/paired t-test compare

Answer 13

means of 2 groups

Question 14

What are the requirements and assumptions of T-tests

Answer 14

n>30 for each population
data is continuous
data is a random sample and normally distributed
each population should have the same variance

Question 15

WHat are the different types of t tests

Answer 15

one sample t test
independent t test
dependent t test

Question 16

What is a one sample t test

Answer 16

compare a group’s mean to a benchmark group

Question 17

What is an independent t test

Answer 17

compare 2 independent groups

Question 18

What is a dependent t test

Answer 18

compare 2 groups that are somehow related

Question 19

When do you use a 1-tailed t test

Answer 19

population is significantly greater than the other

Question 20

When do you use a 2-tailed t test

Answer 20

population is significantly different from the other population

Question 21

What is the use of ANOVA

Answer 21

to compare the means of 3 or more groups

Question 22

What are the rules and assumptions of ANOVA

Answer 22

compares all groups at once
tell you there is a difference between at least 2 groups
examines variance from mean scores
takes deviation for mean, square and sum= sum of squares

independent observations
normally distributed data
homogeneity of variance

Question 23

What is needed after ANOVA

Answer 23

post-hoc test

Question 24

WHat are the types of post hoc tests

Answer 24

Turkey test

Dunnett’s

Question 25

What is a Turkey post hoc test

Answer 25

compares each group to every other group

Question 26

What is a Dunnett’s post hoc test

Answer 26

compares all groups to a control group

Question 27

What are the nonparametric tests

Answer 27

Mann Whitney U test
Wilcoxon Signed ranks
Kruskal Wallis

Question 28

What does a Mann Whitney U test measure

Answer 28

RANKS instead of actual values

Question 29

What does a WIlcoxon Signed Rank test measure

Answer 29

absolute values of differences are sorted and ranked

Question 30

WHat is the alternative for independent t-test if there is skewed data

Answer 30

mann-whitney u test

Question 31

What is the alternative for dependent t-test if there is skewed data

Answer 31

wilcoxon signed ranks

Question 32

What is the alternative for ANOVA if there is skewed data

Answer 32

Kruskal Wallis

Question 33

Do you still need a post hoc test with a Kruskal Wallis

Answer 33

yes

Question 34

When is a box and whisker plot used

Answer 34

not a normal distribution