Bioestadística

Question 1

The ratio of the probability of an outcome occurring in an exposed group to the probability of the outcome occurring in an unexposed group.

Answer 1

Relative risk
Risk in treatment/risk in control group

Question 2

1-Risk in treatment/risk in control group

Answer 2

Relative risk reduction

Question 3

The difference in risk attributable to an exposure as compared to non-exposure (i.e., ARR = risk in non-exposed group – risk in exposed group).

Answer 3

Absolute risk reduction

Question 4

After learning in a lecture that cesarean delivery rates vary from < 0.5% to over 30% across countries, a medical student wants to investigate if national cesarean section rates correlate with national maternal mortality rates worldwide. For his investigation, the student obtains population data from an international registry that contains tabulated cesarean section rates and maternal mortality rates from the last 10 years for a total of 119 countries. Which of the following best describes this study design?

Survival analysis
Case series
Meta-analysis
Case-control study
Cross-sectional study
Retrospective cohort study
Ecological study
Prospective cohort study

Answer 4

Ecological study

An ecological study is an observational study that assesses data collected at the population level for exposures and/or outcomes

Question 5

In a ______ study, every participant receives all the interventions but at different times and/or in a different sequence. In the study described in this vignette, all the participants sequentially received tDCS and sham tDCS (i.e., the groups crossed over). A washout period between treatments is commonly included in crossover studies to enable any effects of the first treatment to wear off prior to starting the sequential treatment. ____ designs are best suited to study interventions with a temporary effect for chronic diseases with a stable state during the study period. They are not suitable for studying acute conditions or interventions with a permanent or long carry-over effect (e.g., vaccinations, surgery).

Answer 5

crossover

Question 6

______ is the proportion of individuals who developed an illness within a given period of time to the number who were exposed.

Answer 6

Cumulative incident