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The Reed–Frost model is a mathematical model of epidemics put forth in the 1920s by Lowell Reed and Wade Hampton Frost, of Johns Hopkins University.〔Schwabe CW, Riemann HP, Franti CE. Epidemiology in Veterinary Practice. Lea & Febiger, 1977. Pp 258–260〕〔Abbey H. 1952. An examination of the Reed-Frost theory of epidemics. Hum. Biol. 3:201〕 This is an example of a "chain binomial" model, a simplified, iterative model of how an epidemic will behave over time. The Reed–Frost model is based on the following assumptions:〔http://www.osc.edu/education/si/projects/epidemic〕 1. The infection is spread directly from infected individuals to others by a certain type of contact (termed "adequate contact") and in no other way. 2. Any non-immune individual in the group, after such contact with an infective individual in a given period, will develop the infection and will be infectious to others only within the following time period; in subsequent time periods, he is wholly and permanently immune. 3. Each individual has a fixed probability of coming into adequate contact with any other specified individual in the group within one time interval, and this probability is the same for every member of the group. 4. The individuals are wholly segregated from others outside the group. (It is a closed population.) 5. These conditions remain constant during the epidemic. The following parameters are set initially: :- Size of the population :- Number of individuals already immune :- Number of cases (usually set at 1) :- Probability of adequate contact With this information, a simple formula allows the calculation of how many individuals will be infected, and how many immune, in the next time interval. This is repeated until the entire population is immune, or no infective individuals remain. The model can then be run repeatedly, adjusting the initial conditions, to see how these affect the progression of the epidemic. The probability of adequate contact corresponds roughly with R0, the basic reproduction number. ==References== 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Reed–Frost model」の詳細全文を読む スポンサード リンク
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