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A retrospective study, on the other hand, 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 1926 investigation of risk factors for breast cancer, were retrospective investigations.
Since 2016 similar episodes of mass psychogenic illness has been occurring in the same school every year. In 2016, twelve students were affected and in 2017, a total of 18 students of the same school were affected showing various symptoms in a single day. Hence it was thought to be a unique case of recurrent mass hysteria. [63] [64]
Research design refers to the overall strategy utilized to answer research questions. A research design typically outlines the theories and models underlying a project; the research question(s) of a project; a strategy for gathering data and information; and a strategy for producing answers from the data. [ 1 ]
A case study is an in-depth, detailed examination of a particular case (or cases) within a real-world context. [1] [2] For example, case studies in medicine may focus on an individual patient or ailment; case studies in business might cover a particular firm's strategy or a broader market; similarly, case studies in politics can range from a narrow happening over time like the operations of a ...
This example of design experiments is attributed to Harold Hotelling, building on examples from Frank Yates. [21] [22] [14] The experiments designed in this example involve combinatorial designs. [23] Weights of eight objects are measured using a pan balance and set of standard weights. Each weighing measures the weight difference between ...
Scenarios in which a global catastrophic risk creates harm have been widely discussed. Some sources of catastrophic risk are anthropogenic (caused by humans), such as global warming, [1] environmental degradation, and nuclear war. [2] Others are non-anthropogenic or natural, such as meteor impacts or supervolcanoes.
Germany searched on Monday for answers on possible security lapses after a man drove his car into a Christmas market, killing at least five people and casting a renewed spotlight on security and ...
A backdraft (North American English), backdraught (British English) [1] or smoke explosion is the abrupt burning of superheated gases in a fire caused when oxygen rapidly enters a hot, oxygen-depleted environment; for example, when a window or door to an enclosed space is opened or broken. Backdrafts are typically seen as a blast of smoke and ...