The question below refers to a large, multicenter, population based epidemiologi

Question

The question below refers to a large, multicenter, population based epidemiological study in England and Wales, which included two rural and three urban centers. A subset of this population based study was used for all subsequent analysis in order to analyze the survival times of patients with incident cases of dementia. A total of 438 incident dementia cases were identified. These 438 individuals were then followed for the next 10 years. They were interviewed every three months and the exact date of death for all participants was recorded (if death occurred during the 10 year study window and if the participant had not withdrawn from the study). a. Referring to the sample of 438 incident dementia cases, what type of study is described? b. Kaplan-Meier (KM) methods would be used to determine estimated survival time (in years) for all incident dementia cases. Right censoring will be observed due to death and study attrition/dropout. This censoring, in order for KM methods to be valid, must adhere to what assumption/requirement? c. Assume that we only look at 13 of these study participants. Survival rimes (in years) are as follows, where '+' indicates a censored observation: 0.5+, 1.4, 2.3, 2.5, 2.5+, 4.3, 4.9, 4.9, 5.2, 7.0+, 7.0+, 7.2, 10+ Fill out the below table for the survival function, based on the 13 observations above. Assume the 13 observation are representative of the entire population of dementia incident cases.

Explanation / Answer

a) It is survival analysis.

b) Assumption of independence of censoring times is required to get unbiased & reliable estimates.small sample size & heavy censoring may also affect the reliability of Kaplan Meir estimates. Similarly , lack of independence within the sample, lack of independence of censoring & lack of uniformity within a time interval may also can affect the reliability of estimates.

c)

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