Statistics

Question 1

Standard error of mean

Answer 1

Standard deviation/square root (number of patients)

Question 2

NNT

Answer 2

1/absolute risk reduction

Question 3

Variance

Answer 3

SD squared

Question 4

Study design - outcome measure is relative risk

Answer 4

Cohort Study

Question 5

Groups selected based on exposure to e.g toxin and followed up to see if they develop the disease

Answer 5

Cohort study

Question 6

Study design - outcome measure is odds ratio

Answer 6

Case-control

Question 7

Patients with particular condition identified and matched with controls then look at past exposure to possible causal agent

Answer 7

Case-control

Question 8

Error: the null hypothesis is rejected when it is true

Answer 8

Type 1, not affected by sample size

Question 9

Error: the null hypothesis is accepted when it is false

Answer 9

Type 2, affected by sample size

Question 10

Probability of correctly rejecting the null hypothesis when it is false

Answer 10

Power - increase by increasing sample size

Question 11

Probability of obtaining a result by chance at least as extreme as the one actually observed assuming null hypothesis is true

Answer 11

P value

Question 12

Non-parametric, unpaired data

Answer 12

Mann-Whitney U

Question 13

Non-parametric, paired ‘before’ and ‘after’ on same population

Answer 13

Wilcoxon

Question 14

Non-parametric, proportions/percentages

Answer 14

Chi-squared

Question 15

Non-parametric, correlation

Answer 15

Spearman, Kendall

Question 16

Parametric, correlation

Answer 16

Pearson’s

Question 17

Likelihood ratio for positive result

Answer 17

sens/1-spec

Question 18

Likelihood ratio for negative result

Answer 18

(1-sens)/spec

Question 19

Relative risk ratio

Answer 19

EER/CER

Question 20

Relative risk reduction

Answer 20

(EER-CER)/CER