Biostats (NAPLEX)

__% of values fall within 1 SD of the mean in Gaussian distribution

68%

__% of values fall within 2 SD of the mean in Gaussian distribution

95%

____ is the better measure of central tendency in skewed data?

median

what is the null hypothesis (H0)?

states theres no statistical significance between groups

what is the alternative hypothesis (Ha)?

states there is a statistical significance between groups

how to interpret a CI for difference data?

if the CI range does not include zero, the result is statistically significant

how to interpret a CI for ratio data (RR, OR, HR)?

if the CI does not include a 1, the result is statistically significant

what is a type I error?

null hypothesis was rejected in error - false positive

what is a type II error?

null hypothesis was accepted when it should have been rejected - false negative

what is used to determine type II errors?

beta

what is a study power?

the probability that a test will reject the null hypothesis correctly (avoid a type II error)

relative risk interpretation

RR = 1: no difference

RR >1: greater risk in treatment group

RR <1: lower risk in treatment group

what is a case-control study?

compares patients with a disease (cases) to those without a disease (controls) retrospectively (past)

what is a cohort study?

compares outcomes of a group exposed vs not exposed prospectively (future) and retrospectively (past)

Phase I-IV clinical trials

I: 20-100 health volunteers with the disease (safety, dosage)

II: 100-300 people with the disease (efficacy, ADRs)

III: 300-3000 people with the disease (Efficacy compared to placebo, ADRs)

IV: Post-market surveillance

Sensitivity

How effective a test identifies patients that have the condition

100% = positive in all patients with the condition

Selectivity

How effectively a test identifies patients without the condition

100% = negative in all patients without the condition

What is a cross sectional survey?

Estimates relationship between variables and outcomes at a specific time in a defined population

What are case report and case series?

Describes an adverse reaction or unique condition in a single patient or a few patients

What is a meta-analysis?

Combines results from multiple studies to develop a conclusion with greater stastical power

What is a systematic review article?

Summary of clinical literature that focuses on a specific topic or question

Ranking of reliable medical studies

1- Systematic reviews/meta analysis

2- Randomized controlled trials

3- Cohort studies

4- Case-controlled studies

5- Case series and case reports

6- Expert opinion

What is cost-minimization analysis?

Comparing treatments that have the same efficacy and safety (brand to generic)

What is cost-benefit analysis?

Determining whether benefits outweigh costs

What is cost effectiveness analysis?

Comparing treatments with different costs and effectiveness

What is cost-utlity analysis?

Comparing treatments that affect both quantity and quality of life