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

Ask an Expert

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

Write your message here..

Related Questions

Cauchy distribution, Cauchy distribution : The probability distribution, f ... Cauchy distribution : The probability distribution, f (x), can be given as follows   where α is the position of the parameter (median) and the beta β a scale parameter. Moments

Data monitoring committees (dmc), Committees to monitor the accumulating da... Committees to monitor the accumulating data from the clinical trials. Such committees have chief responsibilities for ensuring the continuing safety of the trial participants, rele

Concordant mutations test, Concordant mutations test : A statistical test u... Concordant mutations test : A statistical test used in the cancer studies to determine whether or not a diagnosed second primary tumour is biologically independent of the original

Breusch-pagan test, The Null Hypothesis - H0:  There is no heteroscedastici... The Null Hypothesis - H0:  There is no heteroscedasticity i.e. β 1 = 0 The Alternative Hypothesis - H1:  There is heteroscedasticity i.e. β 1 0 Reject H0 if Q = ESS/2  >

Partial least squares, Partial least squares is an alternative to the mult... Partial least squares is an alternative to the multiple regressions which, in spite of using the original q explanatory variables directly, constructs the new set of k regressor v

Response feature analysis, Response feature analysis is the approach to th... Response feature analysis is the approach to the analysis of longitudinal data including the calculation of the suitable summary measures from the set of repeated measures on each

Relative poverty statistics, Relative poverty statistics is the statistics... Relative poverty statistics is the statistics on the properties of populations falling below given fractions of average income which play a central role in debate of poverty. The

Growth curve analysis, Growth curve analysis is t he general term for metho... Growth curve analysis is t he general term for methods dealing with development of the individuals over time. A classic instance includes recordings made on a group of children, sa

Relative risk, Relative risk is the measure of the association between the... Relative risk is the measure of the association between the exposure to a particular factor and the risk or probability of a convinced outcome, calculated as follows     therefor

Clustered data, Clustered data : The term applied to both the data in whic... Clustered data : The term applied to both the data in which the sampling units are grouped into the clusters sharing some common feature, for instance families or geographical reg