A simple computer program for creating exact person/time data for use in cohort studies was described. The program was developed to create stratified person/time tables by counting each day from the date of first observation to the date of last observation for each person in the cohort. After the last day of observation, the vital status of each subject was determined. If the subject had died, a death was recorded and classified by the same levels of the variables recorded at the last day of observation. By this procedure, a temporary multidimensional array in which followup of each subject was counted could be created. Since this was actually a temporary array, a large number of cells could be included in a quickly constructed table. Within this array, an ongoing count of the number of person/days of observation could be kept, each being classified for followup according to the variables of interest. The program could categorize followup time and events by any desired unit of person/time. The program requires only a simple data file such as date of first observation, date of last observation, and an indicator of outcome status for each subject to create a simple person/time table. Sample SAS programs for calculating person/time data for crude outcome rates and for creating person/year tables stratified by age, race, gender, birth cohort, cumulative dose, and calendar year were presented. Sample SAS and BASIC programs for calculating data needed computing crude outcome rates were also presented.
We take your privacy seriously. You can review and change the way we collect information below.
These cookies allow us to count visits and traffic sources so we can measure and improve the performance of our site. They help us to know which pages are the most and least popular and see how visitors move around the site. All information these cookies collect is aggregated and therefore anonymous. If you do not allow these cookies we will not know when you have visited our site, and will not be able to monitor its performance.
Cookies used to make website functionality more relevant to you. These cookies perform functions like remembering presentation options or choices and, in some cases, delivery of web content that based on self-identified area of interests.
Cookies used to track the effectiveness of CDC public health campaigns through clickthrough data.
Cookies used to enable you to share pages and content that you find interesting on CDC.gov through third party social networking and other websites. These cookies may also be used for advertising purposes by these third parties.