Residual plots, Advanced Statistics

Residual plots are the plots of some type of residual which might be helpful in assessing the assumption made by the fitted model. In regression analysis there are various methods of plotting the residual values which can be helpful in assessing particular components of the regression model. The most useful plots when diagnosing the linear regression models are given below;

* A boxplot or probability plot of the residuals can be useful in checking for symmetry and specifically for normality of the error terms in the regression model.

* Plotting the residuals against the corresponding values of the explanatory variable.

Any sign of curvature in the plot might suggest that say a quadratic term in the explanatory variable should be included in the model.

* Plotting residuals against fitted values of the response variable. If the variability of the residuals appears to increase with the increase in the size of the fitted values, a transformation of the response variable former to fitting is indicated.

Figure shows some idealized residual plots that indicate particular points about models.

* Figure (a) is what is looked for to confirm that the fitted model is appropriate,

* Figure (b) suggests that the assumption of constant variance is not justified so that some transformation of the response variable before fitting might be sensible,

* Figure (c) implies that the model requires a quadratic term in the explanantory variable.

 

Posted Date: 8/1/2012 12:46:34 AM | Location : United States







Related Discussions:- Residual plots, Assignment Help, Ask Question on Residual plots, Get Answer, Expert's Help, Residual plots Discussions

Write discussion on Residual plots
Your posts are moderated
Related Questions
Two-phase sampling is the sampling scheme including two distinct phases, in the first of which the information about the particular variables of interest is collected on all the m

Procrustes analysis is a technique of comparing the alternative geometrical representations of a group of multivariate data or of the proximity matrix, for instance, two competing

Attack rate : This term frequently used for the incidence of the disease or condition in the particular group, or during a limited interval of time, or under the special circumstan

MEANING ,IMPORTANCE AND RELEAVANCE OF SCATTER DIAGRAM

Method of moments   is the procedure for estimating the parameters in a model by equating sample moments to the population values. A famous early instance of the use of the proced

The model which is applicable to the longitudinal data in which the dropout process might give rise to the informative lost values. Specifically if the study protocol specifies the

Pasture trials is the study in which the pastures are subjected to number of treatments (types of forage, animal management systems, agronomic treatments, and many more)The grazin

How large would the sample need to be if we are to pick a 95% confidence level sample: (i) From a population of 70; (ii) From a population of 450; (iii) From a population of 1000;

Regression to the mean is the procedure first noted by Sir Francis Galton that 'each peculiarity in man is shared by his kinsmen, but on average to the less degree.' Hence the ten

Product-limit estimator is a method for estimating the survival functions for the set of survival times, some of which might be censored observations. The logic behind the procedu