22 Appendix A: Terms and Definitions

Need to sort and define:

Terms to add to R Notes: * Probability. Look up * Risk. 57, but look up. * Incidence time. 58 * Censoring. 59 * Person time at risk. 60 * Incidence rate. 61 * Inverse time. I think it just means per year, per month, per week, etc. 61

22.1 ⭐️Overview

There are so many terms in epidemiology that are used inconsistently. This note is supposed to help keep track of them all.

22.2 🌎Useful websites

22.3 📖Terms

22.3.1 General Terms

🗒Side Note: At some point, you may want to improve the organization of this note and/or add some graphics.

Cohort. A group of persons for whom membership is defined in a permanent fashion, or a population in which membership is determined by satisfying a set of defining events and so becomes permanent. An example of a cohort would be the members of the graduating class of a school in a given year… With this definition, the members of any cohort constitute a closed population along the time axis in which the chronologically last defining event (e.g., birth with Down syndrome or study recruitment) is taken as the index time.2

Closed population. A closed population adds no new members over time and loses members only to death.2

Open population. Open populations may gain members over time, through immigration or birth, or lose members over time through emigration or death.2 Think of a population defined by a geographic area or political boundary.

22.3.2 General statistics terms

Odds.

Proportion.

Percentage.

Ratio.

22.3.3 Measures of occurence

Incident. A single occurrence of an outcome of interest. We might also talk about the number of incident cases.

Incidence.

Incidence proportion.

Prevalence.

1.
Wickham H, Bryan J. R Packages. second.; 2022.
2.
Lash TL, Rothman KJ. Measures of occurrence. In: Modern Epidemiology. fourth. Wolters Kluwer; 2021:53-77.
3.
Xie Y. Bookdown: Authoring books and technical documents with R markdown. Published online July 2021.

References

2.
Lash TL, Rothman KJ. Measures of occurrence. In: Modern Epidemiology. fourth. Wolters Kluwer; 2021:53-77.