ipl-logo

The Cox Proportional Hazard Model

705 Words3 Pages

Cox Proportional Hazard model is a popular model in survival analysis for detecting the effect of some set of variables on the Hazard. This model is popular largely because there is no need to consider specific distribution function to the hazard function. In Cox proportional hazard model Is Unspecified and non-negative function of time that called a baseline hazard function and is a matrices of covariates related to the ith person. One of the important assumptions in Cox model is that the covariate has a linear effect on the log hazard function. However, Continuous variables can be an influence on the risk with non-linear forms and ignoring this can alter the results.
Adding a nonlinear function to a variable in the Cox model needs …show more content…

Unlike polynomials, allow for a more local fit to the data and fitting after the knots can be limited to the linear. Generally, there are three methods to estimate splines: smoothing splines, polynomial splines and penalized splines. Better performance of polynomial splines depends on the number and location of knots. To overcome this problem, smoothing splines uses all of points as knots. But when you have a large number of discrete time points, the number of parameters that must be estimated to be high and this is will be complicated calculations. Smoothing splines like polynomial splines use a large number of knots, while reduce the influence of knots with a penalized term. Penalized spline is very similar to smoothing splines, but use a fewer knot …show more content…

For example, restricted cubic spline, which is also known as natural cubic splines, is the limited cubic spline that the tails are limited to linear. In this method, the number of knots previously known and their positions are based on data quantile. In this paper, three smoothing methods that have been used in the last decade in medicine and epidemiology studies have examined: Penalize spline, restricted cubic spline and natural spline. All these methods can easily include to the Cox and linear models.

In this analytical study to determine the nonlinear effects of covariate three non-parametric methods Penalize spline, restricted cubic spline and natural spline in Cox model were used. The ability of nonparametric methods was evaluated to recover the true functional form of linear, quadratic and nonlinear functions, using different simulated sample sizes. Data analysis was carried out using R 2.11.0 software and significant levels were considered 0.05.
Spline:
The most common method of estimating function of f in equation (1) is the use of splines. Spline linear estimator is as

Show More
Related
418 Words | 2 Pages

To explain this estimator take the following example: Let S(t) be the probability that a member from a given population will have a lifetime exceeding time, t. For a sample of size N from this population, let the observed times until death of the N sample members be t_1≤t_2≤t_3≤〖… t〗_N Corresponding to each ti is ni, the number "at risk" just prior to time ti, and di, the number of deaths at time ti. Note that the intervals between events are typically not uniform. For example, a small data set might begin with 7 cases. Suppose the survivals of these seven patients (sorted by length of years) are: 1, 2+, 3+, 4, 5+,10, 12+.

Read More
484 Words | 2 Pages

The total cost of computer hardware and software is accounted for within the capital expenditures in the healthcare organization’s financial budget and can be reduced over years to come. Receiving in-kind donations, contributions, or grants should be figured in for this classification, with the price of the donations being the main factor. Also, there might be a labor factor that should be calculated in to establish the overall acquisition cost. Since, technology requests usually demand specialized expertise and knowledge, colleagues of the technological team or external consultants might be required as essential participant of the process, but this would include an opportunity expense or a total consulting expense.

Read More
525 Words | 3 Pages

Many people in the company need access to data to help them do their job better. The main questions revolve around who needs what data, and who chooses what data gets to be shared. Looking at all the pieces, as well as the IT and information assets, the governance of the data belongs to a data owner (Khatri & Brown, 2010). The main questions to be answered must include who is the data owner? Who is responsible for data quality?

Read More
961 Words | 4 Pages

Using FIT with theses adjusted patterns I feel confident that I will complete this assignment

Read More
1483 Words | 6 Pages

The political theorists David R. Mayhew, Gary W. Cox, and Matthew D. McCubbins argue on how the US Congress functions. They focus on the members of Congress and their actions. The basis of disagreement between the theorists lies in what Congress members find of importance. Mayhew argues that members of Congress, primarily concern themselves with reelection, as such, any action taken only benefits that. Cox and McCubbins’, however, formulate that Congress functions on the basis of majority party control and unity.

Read More
3223 Words | 13 Pages

The predicted and experimental responses are compared in order to validate the model and to calculate the prediction error. The prediction error was found to be below 7% indicating that the observed responses were very close to the predicted values. Percentage prediction error is useful in constituting the validity of generated equations and describes how close the predicted responses to that of actual values. The values of <15 are desirable to have closeness of the predicted values with the actual values

Read More
530 Words | 3 Pages

I will choose observational retrospective cohort design for my study. My research question was to identify the association between socioeconomic, biopsychosocial, environmental and genetic factors, and the development of childhood asthma. To establish the effect of allergen (cockroaches, dust), poverty, poor air ventilation in a house, racial factors and air pollution on developing children asthma, a cohort have to have a exposure and the cohort need to followed over time. Cohort studies are used to study the incidence, causes, natural history of a disease and prognosis.1 Because they measure events in the chronological order, they can be used to distinguish between cause and effect.1 This type of study is the best method for determining the incidence and natural history of a disease or condition.1 One of the advantages of doing retrospective cohort study is that the data already collected for some other research study or purposes. The cohort is “followed up” retrospectively.1

Read More
701 Words | 3 Pages

No one should ever put themselves in harm 's way. Most of the time people don’t know what they are doing. Most people try things and try to attempt many reckless and dangerous things without knowing exactly what they are doing in those situations. That’s why you are responsible for your own actions in a life-or-death situation.

Read More
778 Words | 4 Pages

The practical use for this amendment was obviously needed because the punishments used back in those early times was much more aggressive and cruel. The death rate that came with the amount of these punishments was out of hand, and obviously now we don’t see any cruel punishments like they used to. There are still cruel punishments but the amendment made them more suppressed and reduced the number of them drastically. The Amendment was a safeguard for the American people.

Read More
1436 Words | 6 Pages

Understanding the risk and protective factors of child delinquency is imperative in order to create and implement treatment and intervention programs. Because children’s behavior develops during the first five years, it is important to know what risk and protective factors could increase the likelihood of a child becoming a child offender (Wasserman et al., 2003). Moreover, overcoming the risk factors would help prevent the child offender from becoming a juvenile, and later, adult offender. As Wasserman et al (2003) stated, “risk factors for child delinquency operate in several domains: the individual child, the child’s family, the child’s peer group, the child’s school, the child’s neighborhood, and the media” (pg.1). As one can see, children are exposed to risk in partially every aspect of their lives.

Read More
502 Words | 3 Pages

The core assumptions of the Health Belief Model (HBM) are based on the premise that a person will develop a health behavior and is willing to take action to avoid the occurrence of the disease. Furthermore, the person needs to believe that they have the possibility of developing the disease, that they can avoid the disease, that the cost of the change outweighs the benefit and that the person can effectively implement the recommended behavior. Furthermore, the major concepts of the HBM are perceived severity, perceived benefit, perceived barriers, cues to action and self-efficacy (de Chesnay and Anderson, 2016, p. 155-156). According to the Common Sense Model (CSM), when a health threat is perceived by the individual, they progress through three stages: (1) mental representations of the health threat; (2) coping actions or behaviors that help the individual cope with the health threat; and (3) how well the coping strategies manage the

Read More
930 Words | 4 Pages

Hair texture should always be considered first before carrying out a cutting service. The texture of the client's hair will determine how the hair lays once it is cut. Various textures will lead to different looks on different clients depending on the texture of their hair. Natural Hairline And Neck Shape Cutting hair to the natural hairline influences the hairstyle presentation and regrowth.

Read More
1039 Words | 5 Pages

The data for this thesis paper will be obtained from research online, from

Read More
844 Words | 4 Pages

The importance of Epidemiology and how it relates to Nursing Epidemiology is the study of the distribution and determinants of health related states or events including disease and the application of the study to the control of disease and other health problem. Various methods can be used to carry out epidemiological investigation; surveillance determinants. The important of epidemiology on the whole is to improve the health of population. This essay will focus on the importance of epidemiology and how it relates to nursing .There will be definition of health, disease and nursing.

Read More
1977 Words | 8 Pages

Insurance is the equitable transfer of risk of a loss, from one entity in exchange of money. In today’s world, it is difficult to find a person who is not fully insured. Thus, insurance is a means to manage possible risks, as no one wants to face any type of a loss. It is evident that the insurance companies are now profiting to a greater extent since everyone wants to be on a safer side and avoid risks. This has in turn helped in the economy’s development and growth.

Read More

More about The Cox Proportional Hazard Model

Related Topics

Open Document