RUP is a fully developed demographic projection program for preparing cohort-component projections for population defined either in five- or single-year age groups one year at a time. The cohort component method projects each age and sex cohort over time based on the components of growth. Annual births create new cohorts, while existing cohorts are decreased by mortality and either increased or decreased by migration.

The RUP program has features that allow a considerable amount of flexibility for specifying fertility, mortality, and migration. As a result, RUP can be used to produce estimates for years where data on these components are available followed by projections into the future. RUP also includes a wealth of output options that allow a detailed examination of the results. These features are described below:

1. The projection is performed by single years of age. This feature allows you to obtain results for special age groups that do not fall into conventional 5-year age groups. It also allows you to track population cohorts that may be smaller or larger than surrounding cohorts due to past demographic events.
2. The projection is performed year by year. This feature allows you to input information on demographic events for a particular year (e.g., excess mortality due to an earthquake) without spreading the effect over a 5-year period. It also provides planners with estimates for each year without having to interpolate between data for surrounding years.
3. Input data for the population and components can be provided in either single ages or 5-year age groups. The age groupings of each item are independent, so you can input 5-year data for some items and single-year data for others. The program converts all data to single years of age before performing the projection.
4. The open-ended age group in your input data can vary between 50 years and over and 100 years and over. In spite of doubts regarding the accuracy of data for the population at the oldest ages, projections should be made using the highest possible open-ended age group to more accurately represent the population dynamics. If you desire, you can still aggregate your results with a younger open-ended age group.
5. The program accepts mortality and fertility rates as input (as do most programs), and it also allows the input of numbers of births, deaths, and/or migrants. This feature allows you to update a base population with recent actual data on vital events. For instance, if your country has census data for 1982 and registered deaths and births as well as migrants from 1982 to 1989, you can include these actual data in the projection without having to estimate rates. In this case, the program would project the 1982 population by age and sex using life tables consistent with the numbers of deaths (by age and/or sex if available) and mortality patterns for surrounding years, age-specific fertility rates consistent with the numbers of births (by age of mother if available), and the known number of migrants for the years 1982 to 1989. For subsequent years, the program would use the projected trend of these components as specified in the input.
6. You can provide input data for any year, including years prior to or following the projection period. The choices for each component (mortality, fertility, international migration, and internal migration) are completely independent. For example, a projection starting in 1970 can have fertility inputs for 1970, 1977, and 1995, and mortality inputs for 1965, 1975, and 2000. Data inputs for years outside the projection period are used to interpolate estimates for years during the projection and/or as patterns of the age structure of the particular component.
7. The program provides output of a wide variety of demographic measures for any specified year of the projection. These outputs include:
   1. Population by sex and age (single years, 5-year age groups, special groups) and summary measures of age (e.g., percentages, sex ratios, median ages, dependency ratios)
   2. Summary vital rates (e.g., crude rates, life expectancy, infant mortality rates, and total fertility rates)
   3. Life tables
   4. Net numbers of migrants or migration rates by age and sex
   5. Number of deaths, by age and sex
   6. Number of births, by age of mother, and age-specific fertility rates

As the name implies, RUP was originally developed for simultaneous projection of two areas (rural and urban); however, the program’s limit to two subpopulations (e.g., populations defined by ethnicity or citizenship) have been updated. Separate RUP projections may be prepared for two or more subpopulations or areas (e.g., administrative regions) and combined to give a fully consistent projected population for a composite area or for a third population defined as the difference between a control projection and N-1 subpopulation projections. Thus, if two areas are projected, RUPAGG can calculate a third area as the sum of the two areas (e.g., total = region 1 + region 2) or as the difference (e.g., region 2 = total – region 1). This flexibility allows a demographer to create a projection model that accurately reflects what is known about the demographic situation in a country, making maximum use of available data. However, this flexibility requires the user (1) to decide on the best way to model the situation (since the program does not limit the options) and (2) to provide best estimates for all projection inputs for each subpopulation or area.

The RUPCombine program allows modeling of population changes due to catastrophic events (e.g., famine or civil conflict) when they are confined to one-half of a calendar year. Such demographic shocks result in relatively large numbers of deaths or migrants within a short period, and the program ensures the numbers are correctly allocated to the half year in which they occur.

The RUPEX Excel interface allows the user to select a RUP, RUPAGG, or RUPCombine input file from a user-defined subdirectory, edit the file, create a duplicate file, print the file, run the projection, and specify and generate output tables and charts for the projection’s base year and for any and all projection years. The graphics capability of the RUPEX interface provides diagnostic tools not previously available to RUP users, allows the user to more easily check the plausibility of assumptions, and to compare projection inputs and outputs dynamically over time.