Search Case Studies LUSAS Bridge is used by engineers worldwide for all types of bridge analysis, design and load rating from simple slab deck bridges, steel trusses, integral bridges and bow-string arch bridges, through to box girder, movable, cable stayed and suspension bridges. It is used routinely for all types of "architectural" bridges with slender or curved shapes, and especially where dynamic loading is important. These case studies provide a number of illustrative uses of the software with the most recently added article at the top. Country flags relate to the project's location.
Introduction A case-control study is designed to help determine if an exposure is associated with an outcome i. In theory, the case-control study can be described simply. First, identify the cases a group known to have the outcome and the controls a group known to be free of the outcome.
Then, look back in time to learn which subjects in each group had the exposure scomparing the frequency of the exposure in the case group to the control group. By definition, a case-control study is always retrospective because it starts with an outcome then traces back to investigate exposures.
When the subjects are enrolled in their respective groups, the outcome of each subject is already known by the investigator.
Advantages of Case-Control Studies Case-control studies have specific advantages compared to other study designs.
They are comparatively quick, inexpensive, and easy. They are particularly appropriate for 1 investigating outbreaks, and 2 studying rare diseases or outcomes.
An example of 1 would be a study of endophthalmitis following ocular surgery. When an outbreak is in progress, answers must be obtained quickly.
An example of 2 would be a study of risk factors for uveal melanoma, or corneal ulcers. Since case-control studies start with people known to have the outcome rather than starting with a population free of disease and waiting to see who develops it it is possible to enroll a sufficient number of patients with a rare disease.
The practical value of producing rapid results or investigating rare outcomes may outweigh the limitations of case-control studies.
Because of their efficiency, they may also be ideal for preliminary investigation of a suspected risk factor for a common condition; conclusions may be used to justify a more costly and time-consuming longitudinal study later. Cases Consider a situation in which a large number of cases of post-operative endophthalmitis have occurred in a few weeks.
The case group would consist of all those patients at the hospital who developed post-operative endophthalmitis during a pre-defined period.
The definition of a case needs to be very specific: Within what period of time after operation will the development of endophthalmitis qualify as a case — one day, one week, or one month?
Will endophthalmitis have to be proven microbiologically, or will a clinical diagnosis be acceptable? Clinical criteria must be identified in great detail. If microbiologic facilities are available, how will patients who have negative cultures be classified?2 Case-Control Studies Overview When the case -control study design is appropriate Benefits Potential biases Variations on the theme Matching Analysis.
Featured Supply Chain articles page, from SCDigest is the industry's best publication and web site for supply chain management and logistics practioners to find information, news, insight, education, opinion and tools.
We cover supply chain, logistics, distribution, RFID, material handling, transportation, supply chain software, manufacturing, supply chain strategy and much more. Many text books have described advantages and disadvantages of cohort and case control studies.
HSE Health & Safety Executive The case for CDM: better safer design a pilot study Prepared by Greenstreet Berman Ltd for the Health and Safety Executive RESEARCH REPORT Having employees apply innovative thinking outside of the scope of their daily functions benefits both employees and employers. A retrospective study looks backwards and examines exposures to suspected risk or protection factors in relation to an outcome that is established at the start of the study. Many valuable case-control studies, such as Lane and Claypon's investigation of risk factors for breast cancer, were retrospective investigations.
The following table summarises useful comments. Electrical Engineering and Computer Science (EECS) spans a spectrum of topics from (i) materials, devices, circuits, and processors through (ii) control, signal processing, and systems analysis to (iii) software, computation, computer systems, and networking.
HSE Health & Safety Executive The case for CDM: better safer design a pilot study Prepared by Greenstreet Berman Ltd for the Health and Safety Executive RESEARCH REPORT Having employees apply innovative thinking outside of the scope of their daily functions benefits both employees and employers.