قسمت دوم 

  3. Controls can be individually matched or frequency matched                                 

 INDIVIDUAL MATCHING: search for one (or more) controls who have the required MATCHING CRITERIA. PAIRED or TRIPLET MATCHING is when there is one or two controls individually matched to each case.

FREQUENCY MATCHING: select a population  of controls such that the overall characteristics of the group match the overall characteristics of the cases. e.g. if 15% of cases are under age 20, 15% of the controls are also.

تو این مورد از همسان سازی فردی و فراوانی صحبت شده که واضح هست

ادامه مطلب

1. Identify the pool from which controls may come.  This pool is likely to reflect the way controls were ascertained (hospital, screening test, telephone survey).

اولین مورد این هست که مشخص کنیم شاهد ها از چه طریقی گرفته میشن مثلا ازبیمارستان یا از طریق تست های غربالگری ویا مطالعات و تحقیقات تلفنی

2. Control selection is usually through matching.

Matching variables (e.g. age), and matching criteria (e.g. control must be withsetin the same 5 year age group) must be up in advance.

درمورد دوم میگه انتخاب شاهد ها بواسطه جور کردن انجام میشه که میتونه بر اساس یه متغیر باشه مثل سن یا یک معیاز که مثلا در گروه های 5ساله همسانسازی بشه

ادامه دارد

سلام به دوستان اگه بادتون باشه که حتما هست دیروز استاد درباره مطالعات مورد شاهد صحبت کردن

بد ندیدم یه مطلبی در این باره بزارم که هم مروری بشه و هم احیانا نکات جدیدی بدست بیاریم

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Definition

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. The goal is to retrospectively determine the exposure to the risk factor of interest from each of the two groups of individuals: cases and controls. These studies are designed to estimate odds.

Case control studies are also known as "retrospective studies" and "case-referent studies."

ادامه مطلب