Biostatistics

Question 1

continuous data

Answer 1

logical order with values that continuously increase (or decrease) by the same amount
-ratio data: 0 = none (age, height, weight)
-interval data: 0 does not equal none (temperature)

Question 2

discrete data

Answer 2

data fits into a limited number of categories
-nominal data: arbitrary order (gender, ethnicity)
-ordinal data: ranked in logical order (NYHA functional class)

Question 3

independent variables

Answer 3

changed by the researchers
-drugs, drug doses, placebos, patients

Question 4

dependent variables

Answer 4

affected by the independent variables
-HF progression, HgbA1c, BO, cholesterol

Question 5

null hypothesis

Answer 5

no statistical difference between groups
-what the researcher tries to disprove or reject

Question 6

alpha level

Answer 6

-maximum permissibke error margin
-set at 5% 0.05

Question 7

comparing P value to alpha

Answer 7

-if alpha is set at 0.05 and the p-value is less than 0.05 the null hypothesis is rejected (statistically significant)
-if p-value is greater than or equal to alpha the study has failed to reject the null hypothesis and the result is not statistically significant

Question 8

confidence interval

Answer 8

CI = 1- alpha

Question 9

Type 1 error: false positives

Answer 9

-conclusion was wrong and type 1 error was made
-alternative hypothesis was accepted and the null hypothesis was rejected in error
-alpha is 0.05 with p < 0.05 = statistically significant and the probability if type I error is < 5% –> 95% confident

Question 10

Type 2 error: false negatives

Answer 10

when null hypothesis is accepted when it should have been rejected ‘
-set at 0.1 or 0.2
-risk incr if sample size is too small

Question 11

study power

Answer 11

to avoid type 2 error

Question 12

relative risk

Answer 12

risk in treatment group/risk in control group

-RR = 1 implies no difference in the risk of the outcome
-RR > 1 implies greater risk of the outcome in the treatment group
-RR < 1 implies lower risk of the outcome on the treatment group

Question 13

Relative risk reduction

Answer 13

(% risk in control group - % risk in tx group) / % risk in the control group

or 1- RR

Question 14

absolute risk reduction

Answer 14

% risk in control group - % risk in tx group

Question 15

NNT/NNH

Answer 15

1 / (risk in control group - risk in tx group)

or

1/ ARR

Question 16

HR

Answer 16

hazard rate in the tx group / hazard rate in the control group

Question 17

OR / HR interpretation

Answer 17

= 1: event rate is the same
> 1: event rate in the tx group is higher
< 1: event rate in the treatment group is lower

Question 18

Case control studies

Answer 18

retrospective comparisons of cases (patients with a disease) and controls (patients without a disease)

Question 19

cohort studies

Answer 19

retrospective or prospective comparisons of patients with with an exposure to those without an exposure

Question 20

randomized controlled trials

Answer 20

prospective comparison of patients who were randomly assign to groups

Question 21

meta-analysis

Answer 21

analyzes the results of multiple studies