# Lecture 3 Flashcards

1

Q

risk

A

- the probably that the outcome will occur given a particular set of circumstances
- also called measures of association

2

Q

risk difference

A

- the risk (incidence) of disease in one group minus the risk (incidence) of disease in another group

3

Q

attributable risk

A

- risk difference when referring to factors that increase the risk of disease
- I_E-I_U

I_E = incidence in exposed I_U = incidence in unexposed

4

Q

attributable risk percent

A

- the percent of the risk in the exposed group that is attributable to the exposure
- percentage of risk among the exposed group that would be eliminated if the exposure had not occurredI_E-I_U

________

I_E

5

Q

absolute risk reduction

A

- the proportion of patients who were spared an adverse outcome due to the treatment

I_C - I_Rx

I_C=incidence in control group

I_Rx=incidence in treated group

6

Q

relative risk

A

- the probability of an outcome given an exposure (risk factor or treatment) compared to the risk without the exposure

RR = I_E/I_U OR

I_Rx/I_C for treatment

7

Q

when the relative risk is greater than 1.0

A

- the exposure or treatment increases the risk of disease

8

Q

when the relative risk is less than 1.0

A

- the exposure or treatment decreases the risk of disease

9

Q

when the relative risk = 1.

A

- the exposure or treatment does not increase or decrease the risk of disease

10

Q

relative risk reduction

A

- the percentage of baseline risk that is removed as a result of a given therapy

RRR = ARR/I_c = (I_c - I_Rx)/I_c

RRR=1-RR

11

Q

number needed to treat

A

- how many patients need to be treated to prevent one outcome event

NNT = 1/ARR

12

Q

standard deviation

A

- a measure of the degree of variability in individual measurements in a study
- how much variability there is in measurements from individuals in a sample

13

Q

for a variable that is distributed normally

A

- 68% of the values will be between one standard deviation

95% will be between two standard deviations

14

Q

standard error

A

- a measure of the dispersion of a sample means around the population mean
- how much uncertainty there is in the group values

standard error = SD/ sqrt (sample size)

15

Q

null hypothesis

A

- there is no difference in outcomes between comparison populations
- Ho is never accepted