Epidemiology/Stats

Question 1

For which study designs does one use risk ratio/rate ratio (relative risk)?

Answer 1

Calculated for study designs that collect data on incidence: cohort and RCT

Question 2

For which study design does one use risk odds ratio?

Answer 2

Calculated for study designs that use prevalent cases: cross-sectional and case-control studies

Question 3

What is type I (alpha) error?

Answer 3

True null hypothesis incorrectly rejected (false positive)

Question 4

What is type II (beta) error?

Answer 4

Failing to reject false null hypothesis

Question 5

Power equation

Answer 5

1 – beta

Question 6

ROC axes?

Answer 6

Sensitivity on Y axis and 1-specificity on X axis

Question 7

ROC AOC?

Answer 7

AOC = accuracy of test

Question 8

Left shift of ROC has what result?

Answer 8

Increased accuracy

Question 9

Parametric vs non-parametric tests in large samples

Answer 9

The nonparametric tests nearly as powerful as the parametric test from Gaussian populations

Question 10

Parametric vs non-parametric tests in small Gaussian samples

Answer 10

Non-parametric tests have much less power

Question 11

Figure out what this means…

Answer 11

 Usually report p values and not CIs because this requires additional assumptions
 Cannot be readily extended to regression models
 Consider transforming data to create a Gaussian distribution rather than use nonparametric and the decision of whether to use parametric vs nonparametric most important with small data sets

Question 12

Parametric and non-parametric tests for 2 means

Answer 12

T test and Mann-whitney U (Wilcoxon Rank Sum) respectively

Question 13

Parametric and non-parametric tests for 2 paired means

Answer 13

Paired t-test and Wilcoxon Signed Rank respectively

Question 14

Parametric and non-parametric tests for 3 means

Answer 14

ANOVA and Kruskal-Wallis respectively

Question 15

Parametric and non-parametric tests for 3 means repeat measurements

Answer 15

Repeated measures ANOVA and Friedman respectively

Question 16

Parametric and non-parametric tests for correlation

Answer 16

Pearson’s coefficient and Spearman’s coefficient respectively

Question 17

2 groups, independent

Answer 17

Chi-Squared, Fisher’s exact

Question 18

2 groups, dependent

Answer 18

McNemar’s Chi squared

Question 19

3 groups, independent

Answer 19

Chi-Squared, Fisher’s exact

Question 20

3 groups, dependent

Answer 20

Cochran’s Q test

Question 21

Association between two variables

Answer 21

Odds Ratio, Relative Risk

Question 22

Goal of regression analysis

Answer 22

To determine the values of parameters for a function that cause the function to best fit a set of data observations that you provide

Question 23

Variables/equation in linear regression

Answer 23

Both continuous variables, straight line equation

Question 24

Logistic regression

Answer 24

Probability of occurrence of an event by fitting data to a logistic curve; generalized linear model used for binomial regression. Makes use of several predictor variables that may be either numerical or categorical

Question 25

COX regression

Answer 25

Survival (multiple groups)