Stats

Question 1

Absolute Risk

Answer 1

of events in treated or control groups

/
# of people total in that group

Question 2

Absolute Risk Reduction

Answer 2

absolute risk in control group (ARC) - absolute risk in treatment group (ART)

Question 3

Group A

Answer 3

-Have disease
-Have exposure

Question 4

Group B

Answer 4

-No disease
-Have exposure

Question 5

Group C

Answer 5

-Have disease
-No exposure

Question 6

Group D

Answer 6

-No disease
-No exposure

Question 7

Relative Risk

Answer 7

ART
/
ARC

OR

A/(A+B)
/
C/(C+D)

Question 8

Relative Risk Reduction

Answer 8

1 - RR (x 100%)

Question 9

Odds Ratio

Answer 9

A/C
/
B/D

Question 10

Odds Ratio Interpretation

Answer 10

< 1 = negative association (protective)

1 = no association

> 1 = positive association (harmful)

Question 11

Number Needed to Treat

Answer 11

1/ARR

Question 12

Sensitivity

Answer 12

ability of a test to detect a true positive

TP/(TP+FN)

Question 13

Specificity

Answer 13

ability of a test to detect a true negative

TN/(TN+FP)

Question 14

Positive Predictive Value

Answer 14

proportion of those w/ disease when test is positive

TP/(TP+FP)

Question 15

Negative Predictive Value

Answer 15

proportion of those w/o disease when test is negative

TN/(TN+FN)

Question 16

Mortality Rate

Answer 16

deaths during specified time interval
/
population size at risk of death

Question 17

Incidence Proportion

Answer 17

new reported cases
/
initial population at risk

*expressed as %

Question 18

Incidence Rate

Answer 18

new reported cases
/
susceptible population

*must subtract those who already had disease from susceptible population

Question 19

Type I Error

Answer 19

concluding there is a difference when one does not exist (rejecting null hypothesis)

probability of making this = alpha

Question 20

Type II Error

Answer 20

concluding there is no difference when one actually exists (null hypothesis not rejected when it should be)

probability of making this = beta

Question 21

Continuous Data

Answer 21

Interval - ranked in specific order + arbitrary zero (ex: degrees F)

Ratio - ranked in specific order + absolute zero (degrees K, weight, BP)

Question 22

Categorical Data

Answer 22

Nominal - classified into groups in unordered manner (ex: race, sex, presence/absence of disease)

Ordinal - ranked in specific order (ex: NYHA class, pain/Likert scale)

Question 23

Statistical tests used for nominal data

Answer 23

2 Groups (Independent) = x2 or Fisher exact test

3+ Groups (Independent) = x2 or Fisher exact test

2 Groups (Dependent) = McNemar test

3+ Groups (Dependent) = Cochran Q test or Mantel-Haenszel test

Chi-Fish, Chi-Fish, McNem, Cock-Mantel

Question 24

Statistical tests used for ordinal data or continuous data (not normally distributed)

Answer 24

2 Groups (Independent) = Mann-Whitney U test or Wilcoxan rank sum test

3+ Groups (Independent) = Kruskal-Wallis test

2 Groups (Dependent) = Wilcoxon signed-rank test

3+ Groups (Dependent) = ANOVA

Man-Wit Cox Rank, KW, Cox Sum, ANOVA

Question 25

Statistical tests used for continuous data (normally distributed)

Answer 25

2 Groups (Independent) = Student t-test

3+ Groups (Independent) = ANOVA test

2 Groups (Dependent) = Paired t-test

3+ Groups (Dependent) = ANOVA

Question 26

When to use mean

Answer 26

continuous + normally distributed data

Question 27

When to use standard deviation

Answer 27

continuous, parametric data

Question 28

When to use median

Answer 28

ordinal or continuous data

Question 29

When to use mode

Answer 29

nominal, ordinal, or continuous data