Biostats

Question 1

Prospective studies

1) Name types of studies (5)
2) Things you can calculate (2)
3) Qualities

Answer 1

Info on incidence of disease based on presence or absence of risk factors

1) Types of studies = observational, longitudinal, cohort, incidence, or follow-up studies
2) Relative risk and incidence
3) Time consuming, expensive, good for common diseases

Question 2

Retrospective studies

1) Name types of study
2) Things you can calculate
3) Qualities

Answer 2

Info about risk factors based on presence (cases) or absence (controls) of disease

1) Case-control
2) Odds ratio
3) Less time-consuming, inexpensive, and practical for rare diseases

Question 3

Case series study

Answer 3

Describes clinical presentation of extremely rare disease; may suggest need for a retrospective or prospective study

Question 4

Prevalence/Cross-sectional survey

Answer 4

Looks at prevalence of disease and its risk factors; suggests a possible cause of disease
- Used to develop a hypothesis for prospective study

Question 5

Type I and II Error

Answer 5

Type I: false positive (claiming an effect or difference when none exists/rejecting null hypothesis when it is true)
- Alpha = prob of making type I error

Type II: false negative (claiming no difference when one exists/accepting null hypothesis when it is false
- Beta = probability of making type II error

Question 6

Power

Answer 6

Probability of rejecting null hypothesis when it is false
- Best way to increase power = increase sample size

Power = 1-beta

Question 7

Number needed to treat

Answer 7

Number of people that need to receive treatment to prevent 1 adverse event

NNT = 1/(ARR)