What are person years and why are they useful in epidemiology?

An incidence rate describes how quickly disease occurs in a population. It is based on person-time, so it has some advantages over an incidence proportion. Because person-time is calculated for each subject, it can accommodate persons coming into and leaving the study.

What does per 100000 person years mean?

Incidence specifies the number of new diagnoses for the at-risk population of a disease. Changing the specified population will also change the incidence. For example, the incidence of stroke is approximately 250/100,000 people-year for all individuals in the United States.

How is person month calculated?

To calculate person months, multiply the percentage of your effort associated with the project times the number of months of your appointment. For example: 25% of a 9 month academic year appointment equals 2.25 (AY) person months (9 x 0.25= 2.25)

What is person time?

Person-time is an estimate of the actual time-at-risk – in years, months, or days – that all participants contributed to a study. The denominator for a rate (person- time) is a more exact expression of the population at risk during the period of time when the change from non-disease to disease is being measured.

What are NSF person months?

The term “person months” refers to the effort – amount of time – that PI/coPI(s), and other senior personnel will devote to a specific project. The effort is based on the organization’s regular academic year, summer, or calendar year.

What is an example of a case control study?

For example, in a case-control study of the association between smoking and lung cancer the inclusion of controls being treated for a condition related to smoking (e.g. chronic bronchitis) may result in an underestimate of the strength of the association between exposure (smoking) and outcome.

How to calculate the age of a person?

Person Age Group Age at Start Age at End Person Years 1 20-<25 24.504 25 0.496 1 25-<30 25 30 5.00 1 30-<35 30 35 5.00 1 35-<40 35 37.501 2.501

Which is the correct method to calculate person years?

1. Exact Method Because administrative data typically contain full information for birthdate, date of event, and date of death, we can use exact dates to calculate person years. However, if the exact dates of birth, entry into and/or exit from the study are unknown, these must be approximated.

What is the lifetime of a variable in a function?

The lifetime of variables inside a function is as long as the function executes. They are destroyed once we return from the function. Hence, a function does not remember the value of a variable from its previous calls. Here is an example to illustrate the scope of a variable inside a function.

What do you mean by estate for years?

An estate for years is a type of lease, with the tenant leasing real property for a specific amount of time. There is a beginning date and an ending date for the lease, and the lease usually lasts for many years. The lease specifies the amount of rent the tenant must pay the landlord.