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Event History Analysis
Survival analysis is a branch of statistics for analyzing the expected duration of time until one event occurs, such as death in biological organisms and failure in mechanical systems. This topic is called reliability theory or reliability analysis in engineering, duration analysis or duration modelling in economics, and event history analysis in sociology. Survival analysis attempts to answer certain questions, such as what is the proportion of a population which will survive past a certain time? Of those that survive, at what rate will they die or fail? Can multiple causes of death or failure be taken into account? How do particular circumstances or characteristics increase or decrease the probability of survival? To answer such questions, it is necessary to define "lifetime". In the case of biological survival, death is unambiguous, but for mechanical reliability, failure may not be well-defined, for there may well be mechanical systems in which failure is partial, a matter of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Proportional Hazards Model
Proportional hazards models are a class of survival models in statistics. Survival models relate the time that passes, before some event occurs, to one or more covariates that may be associated with that quantity of time. In a proportional hazards model, the unique effect of a unit increase in a covariate is multiplicative with respect to the hazard rate. For example, taking a drug may halve one's hazard rate for a stroke occurring, or, changing the material from which a manufactured component is constructed may double its hazard rate for failure. Other types of survival models such as accelerated failure time models do not exhibit proportional hazards. The accelerated failure time model describes a situation where the biological or mechanical life history of an event is accelerated (or decelerated). Background Survival models can be viewed as consisting of two parts: the underlying baseline hazard function, often denoted \lambda_0(t), describing how the risk of event per time ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Survival Tree For Prostate Cancer
Survival, or the act of surviving, is the propensity of something to continue existing, particularly when this is done despite conditions that might kill or destroy it. The concept can be applied to humans and other living things (or, hypothetically, any sentient being), to physical object, and to abstract things such as beliefs or ideas. Living things generally have a self-preservation instinct to survive, while objects intended for use in harsh conditions are designed for survivability. Meaning The word, "survival", derives from the Late Latin '' supervivere'', literally meaning "to outlive". Most commonly, "the term 'survival' means physical survival — that is, a struggle to avoid physical extermination". For example, Charles Darwin's theory of natural selection incorporates the concept of the survival of the fittest in the struggle for existence. Darwin defines the biological concept of fitness as reproductive success, so in Darwinian terms the phrase is best understood a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cox PH Output For Melanoma With Thickness
Cox may refer to: * Cox (surname), including people with the name Companies * Cox Enterprises, a media and communications company ** Cox Communications, cable provider ** Cox Media Group, a company that owns television and radio stations ** Cox Automotive, an Atlanta-based business unit of Cox Enterprises * Cox Models, aka Cox Hobbies * Cox Sports, a regional sports network that served the United States New England region until 2012 Places Antarctica * Cox Glacier * Cox Nunatak * Cox Peaks * Cox Point * Cox Reef United States * Cox, Florida * Cox, Missouri * Cox College (Georgia), a defunct private women's college located in College Park, Georgia * Cox College (Missouri), a private college in Springfield, Missouri * Cox Furniture Store, c. 1890, a historic site in Gainesville, Florida * Cox Furniture Warehouse, a historic site in Gainesville, Florida * Cox Run, a tributary of Little Muncy Creek in Lycoming County, Pennsylvania * Cox site Elsewhere * Cox Island, Cana ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Histograms Of Melanoma Thickness
A histogram is an approximate representation of the distribution of numerical data. The term was first introduced by Karl Pearson. To construct a histogram, the first step is to " bin" (or "bucket") the range of values—that is, divide the entire range of values into a series of intervals—and then count how many values fall into each interval. The bins are usually specified as consecutive, non-overlapping intervals of a variable. The bins (intervals) must be adjacent and are often (but not required to be) of equal size. If the bins are of equal size, a bar is drawn over the bin with height proportional to the frequency—the number of cases in each bin. A histogram may also be normalized to display "relative" frequencies showing the proportion of cases that fall into each of several categories, with the sum of the heights equaling 1. However, bins need not be of equal width; in that case, the erected rectangle is defined to have its ''area'' proportional to the frequency o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cox Proportional Hazards Regression Output For Melanoma Data Set
Cox may refer to: * Cox (surname), including people with the name Companies * Cox Enterprises, a media and communications company ** Cox Communications, cable provider ** Cox Media Group, a company that owns television and radio stations ** Cox Automotive, an Atlanta-based business unit of Cox Enterprises * Cox Models, aka Cox Hobbies * Cox Sports, a regional sports network that served the United States New England region until 2012 Places Antarctica * Cox Glacier * Cox Nunatak * Cox Peaks * Cox Point * Cox Reef United States * Cox, Florida * Cox, Missouri * Cox College (Georgia), a defunct private women's college located in College Park, Georgia * Cox College (Missouri), a private college in Springfield, Missouri * Cox Furniture Store, c. 1890, a historic site in Gainesville, Florida * Cox Furniture Warehouse, a historic site in Gainesville, Florida * Cox Run, a tributary of Little Muncy Creek in Lycoming County, Pennsylvania * Cox site Elsewhere * Cox Island, Cana ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Proportional Hazards Model
Proportional hazards models are a class of survival models in statistics. Survival models relate the time that passes, before some event occurs, to one or more covariates that may be associated with that quantity of time. In a proportional hazards model, the unique effect of a unit increase in a covariate is multiplicative with respect to the hazard rate. For example, taking a drug may halve one's hazard rate for a stroke occurring, or, changing the material from which a manufactured component is constructed may double its hazard rate for failure. Other types of survival models such as accelerated failure time models do not exhibit proportional hazards. The accelerated failure time model describes a situation where the biological or mechanical life history of an event is accelerated (or decelerated). Background Survival models can be viewed as consisting of two parts: the underlying baseline hazard function, often denoted \lambda_0(t), describing how the risk of event per time ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chi-squared Distribution
In probability theory and statistics, the chi-squared distribution (also chi-square or \chi^2-distribution) with k degrees of freedom is the distribution of a sum of the squares of k independent standard normal random variables. The chi-squared distribution is a special case of the gamma distribution and is one of the most widely used probability distributions in inferential statistics, notably in hypothesis testing and in construction of confidence intervals. This distribution is sometimes called the central chi-squared distribution, a special case of the more general noncentral chi-squared distribution. The chi-squared distribution is used in the common chi-squared tests for goodness of fit of an observed distribution to a theoretical one, the independence of two criteria of classification of qualitative data, and in confidence interval estimation for a population standard deviation of a normal distribution from a sample standard deviation. Many other statistical tests a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Log-rank Test
The logrank test, or log-rank test, is a hypothesis test to compare the survival distributions of two samples. It is a nonparametric test and appropriate to use when the data are right skewed and censored (technically, the censoring must be non-informative). It is widely used in clinical trials to establish the efficacy of a new treatment in comparison with a control treatment when the measurement is the time to event (such as the time from initial treatment to a heart attack). The test is sometimes called the Mantel–Cox test. The logrank test can also be viewed as a time-stratified Cochran–Mantel–Haenszel test. The test was first proposed by Nathan Mantel and was named the ''logrank test'' by Richard and Julian Peto. Definition The logrank test statistic compares estimates of the hazard functions of the two groups at each observed event time. It is constructed by computing the observed and expected number of events in one of the groups at each observed event time and t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Life Table For The Aml Data
Life is a quality that distinguishes matter that has biological processes, such as signaling and self-sustaining processes, from that which does not, and is defined by the capacity for growth, reaction to stimuli, metabolism, energy transformation, and reproduction. Various forms of life exist, such as plants, animals, fungi, protists, archaea, and bacteria. Biology is the science that studies life. The gene is the unit of heredity, whereas the cell is the structural and functional unit of life. There are two kinds of cells, prokaryotic and eukaryotic, both of which consist of cytoplasm enclosed within a membrane and contain many biomolecules such as proteins and nucleic acids. Cells reproduce through a process of cell division, in which the parent cell divides into two or more daughter cells and passes its genes onto a new generation, sometimes producing genetic variation. Organisms, or the individual entities of life, are generally thought to be open systems that ma ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Life Table
In actuarial science and demography, a life table (also called a mortality table or actuarial table) is a table which shows, for each age, what the probability is that a person of that age will die before their next birthday ("probability of death"). In other words, it represents the survivorship of people from a certain population. They can also be explained as a long-term mathematical way to measure a population's longevity. Tables have been created by demographers including Graunt, Reed and Merrell, Keyfitz, and Greville. There are two types of life tables used in actuarial science. The period life table represents mortality rates during a specific time period of a certain population. A cohort life table, often referred to as a generation life table, is used to represent the overall mortality rates of a certain population's entire lifetime. They must have had to be born during the same specific time interval. A cohort life table is more frequently used because it is able to ma ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
