How do you calculate patient years?
Patient years are calculated as follows: If 15 patients participated in a study on heart attacks for 20 years, the study would have involved 300 patient years (15 x 20). This number can be divided by the number of patients who have been affected by a certain condition or event.
What are patient years?
A patient experience of 1 year’s duration, e.g., on a waiting list, in a treatment program, under observation, or suffering an illness. One patient-year is equal to, for example, the experience of two patients for 6 months, or 12 patients for 1 month each.
Is 95% confidence interval good?
A smaller sample size or a higher variability will result in a wider confidence interval with a larger margin of error. The level of confidence also affects the interval width. If you want a higher level of confidence, that interval will not be as tight. A tight interval at 95% or higher confidence is ideal.
Where can we use confidence intervals?
Statisticians use confidence intervals to measure uncertainty in a sample variable. For example, a researcher selects different samples randomly from the same population and computes a confidence interval for each sample to see how it may represent the true value of the population variable.
What does 90% mean in a confidence interval?
The “90%” in the confidence interval listed above represents a level of certainty about our estimate.
How to calculate confidence interval for true systolic blood pressure?
Suppose we compute a 95% confidence interval for the true systolic blood pressure using data in the subsample. Because the sample size is small, we must now use the confidence interval formula that involves t rather than Z. The sample size is n=10, the degrees of freedom (df) = n-1 = 9.
Why do we use T values for confidence intervals?
Instead of “Z” values, there are “t” values for confidence intervals which are larger for smaller samples, producing larger margins of error, because small samples are less precise. t values are listed by degrees of freedom (df) which take into account the sample size.
How to get CI for patient-years like this?
See here for an example where confidence intervals are reported for patient years: For MGUS patients we estimated a mortality rate of 52 [95% CI 48-56] per 1000 patient-years, whereas for MGRS patients the rate was 29 [14-58] per 1000 patient-years. How can I get CI for patient-years like this?