Case Control Study Epidemiology Ppt

Case Control Study Epidemiology Ppt-24
Boubekri, M., Cheung, I., Reid, K., Wang, C., & Zee, P. Impact of windows and daylight exposure on overall health and sleep quality of office workers: a case-control pilot study.

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The nested case–control study can be analyzed using methods for missing covariates.

The NCC design is often used when the exposure of interest is difficult or expensive to obtain and when the outcome is rare.

Several studies have used standard cohort analyses to study precursors to breast cancer, e.g.

use of hormonal contraceptives, which is a covariate easily measured on all of the women in the cohort.

However, note that in comparison to the cases, there are so many controls that each particular control contributes relatively little information to the analysis.

If, on the other hand, one is interested in the association between gene expression and breast cancer incidence, it would be very expensive and possibly wasteful of precious blood specimen to assay all 89,000 women without breast cancer.This study would be retrospective in that the former lifeguards would be asked to recall which type of sunscreen they used on their face and approximately how often.This could be either a matched or unmatched study, but efforts would need to be made to ensure that the former lifeguards are of the same average age, and lifeguarded for a similar number of seasons and amount of time per season.Cases and controls should also not be "over-matched." Is the control group appropriate for the population?Does the study use matching or pairing appropriately to avoid the effects of a confounding variable?Individuals with windows in their workplaces had more light exposure, longer sleep duration, and more physical activity.They also reported a better scores in the areas of vitality and role limitations due to physical problems, better sleep quality and less sleep disturbances.A study that compares patients who have a disease or outcome of interest (cases) with patients who do not have the disease or outcome (controls), and looks back retrospectively to compare how frequently the exposure to a risk factor is present in each group to determine the relationship between the risk factor and the disease.Case control studies are observational because no intervention is attempted and no attempt is made to alter the course of the disease.Usually, the exposure of interest is only measured among the cases and the selected controls.Thus the nested case–control study is more efficient than the full cohort design.


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