Terms and Concepts

A description of commonly used terms and concepts in the ComPrev application.

Term	Description
Age Group	A grouping of age ranges together. For example, 5 age groups might comprise the ages 0 – 5, 6 – 15, 16 – 25, 26 – 40, and 40+.
Cohort	A unique collection of values for each of the stratifying variables used. For example, if the 1st stratifying variable has the values Appendix and Stomach, the 2nd stratifying variable has the values Male and Female, and the 3rd stratifying variable has the value White, then the result is 4 cohorts: Appendix / Male / White, Appendix / Female / White, Stomach / Male / White, Stomach / Female / White.
Completeness Index	Proportion of prevalent cases estimated to be observed in limited duration.
Complete Prevalence	Represents the proportion/number of people alive on a certain day who previously had a diagnosis of the disease, regardless of how long ago the diagnosis was, or if the patient is still under treatment or is considered cured.
Data File	A file which contains the raw values.
Data Source	A data file containing the basic parameters used by the ComPrev application.
Dictionary File	A file which contains the defining elements for a data file.
Duration	The length of time in years over which calculations are performed.
Incidence Parameters	A collection of estimates used to estimate incidence rates for specific ages and birth cohorts.
Incidence Rate	The number of new cases per population at risk in a given time period.
Initial Date Of Diagnosis	The date on which the patient was first diagnosed with cancer.
Limited-Duration Prevalence (LDP)	Represents the number of people alive on a certain day who had a diagnosis of the disease within the past x years.
Pivot Value	A variable set to a constant value while all other variables span a range of possible values. Used in a 3 variable comparison to generate a graph where one variable stays a constant value.
Phase of Care	Phase of Care estimation involves looking at consecutive years of limited duration data at the Prevalence Date to partition the incident cases into initial phase of care, last year of life, and the continuing phase of those in between.
Prevalence Date	Prevalence represents new and pre-existing cases alive on a certain date. Only cases diagnosed prior to the prevalence date are included in the analysis.
Prevalence Estimate	An estimate of the number of people alive who had a diagnosis of the disease.
Reference Age	The age to use as the median point of a values distribution.
Relative Risk	The ratio of the probability of a group having the disease versus those that do not.
Standard Error	A measure of the statistical accuracy of an estimate, equal to the standard deviation of the theoretical distribution of a large population of such estimates.
Survival Parameters	Estimated values used in the survival function. In ComPrev, if you import Survival Parameters, these real values can be used for Survival instead of modeled values.
Stratifying Variables	A set of factors used in a data set. There can be a maximum of 10 stratifying variables. The stratifying variables used are not hard-coded into the program. They are determined by the data source used for Comprev (Data.ini and Data.txt). In the ComPrev tutorial (and the default data set), the default variables are Site, Sex, and Race. Site being the specific cancer site, Sex being the sex of the patient, and Race being a population of a specific ethnicity. For each variable, a set of values are used to indicate different groups of data (a cohort).
Survival Rate	The probability of surviving a given length of time after diagnosis.